Reflection sheet and production method therefor and display unit using it

ABSTRACT

A reflective plate comprises a substrate, a plurality of protrusions each formed on the substrate and having a curved surface, and a reflective film formed on the substrate having the protrusions, wherein a planar shape of each of the protrusions is indefinite, and when a frame line of the planar shape of each of the protrusions is divided into fine line segments, the line segments are pointed in all directions or in predetermined directions. This improves reflective properties such as dispersion properties.

TECHNICAL FIELD

[0001] The present invention relates to a reflective plate and a displaydevice that displays images by having the reflective plate utilizingoutside light.

BACKGROUND ART

[0002] These days, mobile information terminals, video recorders, andthe like are being downsized and becoming more and more portable. Thishas presented a problem of how to reduce the power consumption of imagedisplay devices used in those terminals and recorders.

[0003] Image display devices capable of reducing power consumptioninclude reflective type liquid crystal display devices and transflectivetype liquid crystal display devices.

[0004] Reflective type liquid crystal display devices display images byutilizing outside light such as sunlight and indoor lighting andcontrolling the amount of light reflected by a reflective plate. Thismakes a back light needless and realizes a reduction in powerconsumption. In addition, high visibility can be secured for the displayscreen even under strong outside light such as direct sunlight, andtherefore, the display devices are often used in instruments for mobilephones.

[0005] Transflective type liquid crystal display devices display imagesby utilizing light both from outside and the back light. This enables itto turn off the back light when images are displayed in brightsurroundings, and thus realizes a reduction in power consumption. Understrong outside light such as direct sunlight, high visibility can beespecially secured by reflecting outside light. In dark surroundings, onthe other hand, visibility can be secured by turning on the back light.

[0006] Reflective plates equipped in those two types of liquid crystaldisplay devices are preferably without specularity. This is because iflight is specular-reflected, a light source appears on a reflectiveplate and little light is reflected except in this place of appearance,making the display screen dark. In such a case, images are displayedbrightly only when seen from the regularly reflected direction of light,and images are very dark when seen from other directions. That is tosay, brightness can not be secured for displayed images except in theregularly reflected direction of light, and therefore, the displayscreen can not be viewed naturally. In view of this, it is indispensablefor reflected light to be diffused.

[0007] There are mainly two methods to diffuse reflected light.1) Toform the surface of a reflective plate into fine protrusions anddepressions.

[0008] 2) To provide a diffusion film for light diffusion on theviewer's side of a liquid crystal display device.

[0009] In the method 1) among these methods, since reflective propertiesdepend on protrusions and depressions on the surface of the reflectiveplate, the protrusions and depressions are extremely important elementsto decide display properties of a liquid crystal display device.

[0010] However, even if a liquid crystal display device has a reflectiveplate with protrusions and depressions, there is a problem of a darkdisplay screen in dark surroundings with extremely small outside light.Specifically, when outside light comes into the device, the light firstpasses through a liquid crystal layer in a liquid crystal cell. Then,the light is reflected by the surface of the reflective plate on thebackside of the liquid crystal layer, and then passes through the liquidcrystal layer again to be extracted as display light. That is to say,when outside light which has come inside the device goes out of thedevice, the amount of the light is decreased extremely. When the amountof outside light is inherently small, almost none of it is utilized asdisplay light, thus making the display screen dark. Especially for aliquid crystal display device having a color filter to absorb light, theamount of light decreases considerably.

[0011] In view of this, for reflective type liquid crystal displaydevices, it is required to further increase the efficiency of lightutilization. This is preferable also for transflective type liquidcrystal display devices because power consumption is reduced.

[0012] One of methods to increase the efficiency of light utilization isto control the shape of a (diffusion) reflective plate so that incidentlight is reflected over an effective range. In SHARP TECHNICAL JOURNAL,vol. 74 (1999), on pages 41-45, there is disclosed an ideal distributionof tilt angles of protrusions provided on a reflective plate. FIG. 1 isa graph showing the relationship between tilt angles of protrusions andthe presence probability of the tilt angles. A symbol (a) in the figureshows that there is almost no flat portions (where the tilt angle is 0degrees) on the surface of the reflective plate, and protrusions havinga tilt angle of up to about 8 degrees are provided on the surface. Inaddition, the presence probability of the protrusions increases up to 8degrees, and no protrusions of more than 8 degrees of tilt angle exist.In such tilt angle distribution, light is designed to be reflecteduniformly over a range of about 25 degrees from the regularly reflecteddirection, and the light is not dispersed outside the range.

[0013] The reflective properties of a reflective plate having the tiltangle distribution can be described as follows. FIG. 2 is a graphshowing the relationship between an incident angle (degree) of incidentlight and the obtained gain. Gain is a value obtained such that thebrightness of incident light with respect to an incident angle isdivided by the brightness of the incident light with respect to a(diffusion) reflective plate. In the figure, reflective properties inthe case of the ideal tilt angle distribution (corresponding to thesymbol (a) in FIG. 1) are shown as a solid line (a). The viewer looks atthe display screen mostly from the range of 25 degrees from the normaldirection. Therefore, if brightness increases within this range, brightimages are displayed, as in the case of the reflective properties shownas the solid line (a).

[0014] On the other hand, a dotted line (b) shows reflective propertiesin the case of a symbol (b) shown in FIG. 1, where tilt angledistribution is such that the presence probability of the protrusionspeaks at 15 degrees of tilt angle. With such reflective properties,incident light angled by 50 degrees, for example, can be reflectedtowards the normal direction. In other words, incident light angled byvarious degrees is reflected to have widespread and almost uniformbrightness. Therefore, such reflective properties provide high lightdiffusion properties. However, brightness towards the normal directionis lower than the solid line (a). Note that when tilt angle is 20degrees for example, incident light is not released out of the displaydevice.

[0015] In addition, a symbol (c) shown in FIG. 1 is the case where thepeak of the presence probability of the protrusions is in the region ofsmall tilt angles. In this case, regular reflection components increaseand the reflective plate has specularity. Accordingly, obtainedreflective properties are shown as a dotted line (c) in FIG. 2. Suchreflective properties cause extremely large variations in brightnesswith respect to incident angles.

[0016] Thus, since the reflective properties of the reflective platedepend on the tilt angle distribution of the protrusions, it isimportant to control the tilt angle distribution of the protrusions inorder to effectively utilize incident light.

[0017] There are various methods to produce a reflective plate, amongwhich are to roughen the surface of a reflective metal film, and topattern a resin layer to be protrusions and depressions by etching. Whena resin layer is patterned to be protrusions and depressions, the use ofa thermoplastic photo-resist makes it easy to form a uniform pattern.This is specified as follows. FIGS. 3A and 3B are cross sectional viewsillustrating the process of forming a protrusion. First, a photo resistlayer is formed on a substrate 101 and exposed through a mask having apredetermined pattern, and then developed. By these steps, protrusions102 each having a rectangle cross section are formed. Further, byheat-treatment, corner portions of each of the protrusions 102 areheat-fused, forming protrusions 103 each having a smoothly curvedsurface as shown in FIG. 3B. However, if there is a wide distancebetween the protrusions 103, a flat portion 104 is also formed. Thisprovides specularity to the reflective properties of the obtainedreflective plate.

[0018] In Japanese Unexamined Patent Application No. 6-27481A, there isdisclosed a reflective plate that solves the problem of specularity.This publication discloses a reflective plate wherein wave-shapedpicture element electrodes with their upper surfaces being continuousare formed on an insulative substrate. This reflective plate isfabricated as follows. A first polymeric resin layer is formed on theinsulative substrate and patterned to form protrusions. Next, a secondpolymeric resin layer is formed over the insulative substrate havingformed thereon the protrusions in order to fill gaps between theprotrusions. Thereby, the second polymeric resin layer also becomesprotrusion-depression shaped. However, the tilt angles of the secondlayer's protrusions are smaller than those of the protrusions of thefirst layer. In view of this, by reducing flat portions, regularlyreflected light can be reduced. However, in the above-described method,since there is an extra step of coating the second polymeric resin layerand drying it, there arises a problem of increasing fabrication costs.

[0019] In order to solve the problem of increasing fabrication costs,the present inventors attempted a method to form a reflective platehaving a protrusion-depression surface by forming protrusions withoutgaps using a single layer. Specifically, a photo-resist was coated on asubstrate and light-exposed through a mask. A pattern of the mask wassuch that a gap between light shielding portions was set to be 5 μm orless. After the photo-resist was developed, protrusions each having arectangle cross section were formed. Each gaps between the protrusionswas 5 μm or less. Further, the rectangle protrusions were softened anddeformed by heat treatment to fill the gaps therebetween. Among thegaps, gaps of 3 μm or less were filled up and adjacent protrusionsbonded to each other, thus forming a flat portion. As a result, tiltangle distribution was different between a portion in which theprotrusions were distant and a portion in which the protrusions bonded,causing non-uniform reflective properties on the same plane. As aresult, there arose a problem that unevenness was recognized on thedisplay screen. In addition, when a reflective layer made of Al, Ag, orthe like is formed on a source electrode and a drain electrode, there isa danger of a shortcut between the source electrode and the reflectivelayer at a portion without a resist.

[0020] In addition, there is another method that the step of developmentis stopped halfway so that a part of a resist film (hereinafter referredto as a remaining film) remains between the protrusions of the resist.When this method is employed, since the protrusions originally form acontinuous surface, a continuous protrusion-depression surface is formedby melting (heat-fusion). However, the amount of deformation during themelting step varies depending on the thickness of remaining films, andthe amount of deformation decreases as the remaining films becomethinner. Therefore, to control the tilt angles of the protrusions, it isrequired to precisely control the thickness of the remaining films.However, the developing speed of the resist film depends on many factorssuch as temperature, the ability of a developer, and how much the resistfilm is fatigued. This makes it difficult to stop the developmenthalfway and have the same amount of remaining films to control the tiltangles.

[0021] Also in Japanese Patent No. 2698218, there is disclosed a methodto form the protrusion-depression surface of the reflective plate. FIG.4A is a plan view schematically showing a reflective plate disclosed inthis publication. FIG. 4B is a cross section taken along the line A-A inFIG. 4A.

[0022] As shown in FIG. 4A, a multiplicity of protrusions 112 distantfrom one another are provided on a substrate 111, and a reflective film113 is provided to cover the protrusions 112. By providing theprotrusions 112, the reflective plate is provided with light dispersionproperties, and the appearance of a light source on the display screenis reduced. However, in this prior art example, since the protrusions112 are made distant from one another, gap portions 114 are flat. Inaddition, since the area of the gap portions 114 makes up much of thereflective plate as a whole, there is a peak for reflected light in theregularly reflected direction. As a result, a light source appears onthe display screen, causing a problem of making the display screen dark.

[0023] In view of this, a reflective plate that has resolved thisproblem is disclosed in Japanese Patent No. 2756206. FIG. 5A is a planview schematically showing the reflective plate disclosed in thispublication. FIG. 5B is a cross sectional view taken along the line B-Bin FIG. 5A. According to this publication, there are protrusions anddepressions. A first film 122 having protrusions is provided on asubstrate 121. To cover the first film 122, a second film 123 is formed.On the second film 123 is formed a reflective film 124. In such aconfiguration, the formation of the second film 123 smoothes the surfaceof the first film 122 and flat gap portions 125, realizing a smoothlycurved surface in a protrusion-depression manner. This results inremoval of flat portions that were considered as a problem in theforegoing example and realizes preferable light dispersion propertieswithout a sharp peak in the regularly reflected direction.

[0024] However, in the latter prior art example, in the formation of thereflective plate, the step to form the first film 122 having theprotrusions on the substrate 121, and the step to form the second film123 by coating liquid over the first film 122 and hardening the liquidwere required. That is to say, two steps were required to form theprotrusion-depression shape, which was redundant.

DISCLOSURE OF THE INVENTION

[0025] The present invention has been accomplished in view of theforegoing problems, and it is a first object of the present invention toprovide a reflective plate that comprises protrusions having an idealtilt angle distribution with reduced flat portions and is excellent inreflective properties such as dispersion properties, and to provide adisplay device having the reflective plate. A second object of thepresent invention is to provide a fabricating method, wherein variationsin reflective properties resulting from fabrication problems areinhibited to realize an improvement in yields, and a reflective platehaving preferable reflective properties is fabricated.

[0026] (Reflective Plate)

[0027] In order to solve the foregoing problems, there is provided areflective plate comprising a substrate, a plurality of protrusions eachformed on the substrate and having a curved surface, and a reflectivefilm formed on the substrate having the protrusions, wherein a planarshape of each of the protrusions is non-circular, and when a frame lineof the planar shape of each of the protrusions is divided into fine linesegments, the line segments are pointed in all directions or inpredetermined directions.

[0028] In the above-described configuration, when the frame line of theplanar shape of each of the protrusions is divided into fine linesegments, the segments may be pointed in all directions or inpredetermined directions. When the line segments are pointed in alldirections, the surface of each of the protrusions is accordinglypointed in various directions. This is because the surface shape of eachof the protrusions depends on the shape of the frame line of each of theprotrusions. As a result, it is made possible to reflect and diffuseincoming light from an arbitrary direction in various directions, and tohave a constant reflective strength of light irrespective of viewingdirections. That is to say, dispersion properties are improved.

[0029] When the line segments are pointed in predetermined directions,it is made possible to control dispersion properties so that thereflective strength of light has its maximum in predetermineddirections. In other words, in the above-described configuration,dispersion properties can be optimized according to application.Further, the above-described configuration makes it possible to easilycontrol the shape of each of the protrusions only by changing thedirections of the line segments, and this shape controlling is highlyflexible. It should be noted that, in the present specification, aprotrusion is not limited to a surface curved in a protrusion-likemanner, but includes a surface curved in a depression-like manner and ina protrusion-depression-like manner.

[0030] In addition, in order to solve the foregoing problems, there isprovided a reflective plate comprising a substrate, a plurality ofprotrusions each formed on the substrate and having a curved surface,and a reflective film formed on the substrate having the protrusions,wherein a planar shape of each of the protrusions is indefinite, and ashape of a gap portion between the protrusions comprises a curved linehaving a predetermined width and/or a broken line having a predeterminedwidth.

[0031] When the planar shape of each of the protrusions is indefinite,it is made possible that the shape of the gap portion between theprotrusions comprises a curved line and/or a broken line, both having apredetermined width. This enables to minimize the area of the gapportion, compared with the case where uniformly shaped protrusions aredensely disposed. As a result, an increase in reflected light in theregularly reflected direction is inhibited, and an improvement indispersion properties can be realized.

[0032] Here, a width of the gap portion may be uniform.

[0033] Further, the width of the gap portion is preferably in the rangeof 1 to 10 μm.

[0034] A maximum diameter of the planar shape of each of the protrusionsis preferably in the range of 15 to 40 μm.

[0035] A height of each of the protrusions is preferably in the range of1.2 to 4 μm.

[0036] A maximum diameter of the planar shape of each of the protrusionsis preferably from 5 to 20 times larger than the height of each of theprotrusions.

[0037] A contact angle formed by a surface of each of the protrusionsand a surface of the substrate at a contact line is preferably in arange of 10 to 25 degrees.

[0038] The protrusions are preferably disposed 30 or less per area of1×10⁴ μm².

[0039] The protrusions may be provided in positions of meeting arelation of Fibonacci series (corresponding to regular spiralalignment).

[0040] On the other hand, the reflective plate may be such that thesubstrate is light-transmissive, and the gap portion is not coated withthe reflective film and is a light transmission region. Thisconfiguration makes it possible for the reflective plate to be used as atransflective type reflective plate.

[0041] Further, the protrusions may be light-transmissive, and a lowposition portion of each of the protrusions is not coated with thereflective film.

[0042] The low position portion of each of the protrusions may be suchthat, when an angle between the substrate and a tangent line in contactwith the surface of each of the protrusions is taken to be a tilt angle,the low position portion has a tilt angle of 15 degrees or more.

[0043] In the case where the reflective plate of the present inventionis used as a transflective type reflective plate, a width of the gapportion is preferably in a range of 1 to 20 Mm.

[0044] Similarly, in the case where the reflective plate of the presentinvention is used as a transflective type reflective plate, a contactangle is preferably in a range of 10 to 40 degrees.

[0045] Further, in the case where the reflective plate of the presentinvention is used as a transflective type reflective plate, thedistribution of the protrusions is preferably such that the protrusionsare provided 15 or less per area of 1>10⁴ μm².

[0046] In addition, in order to solve the foregoing problems, there isprovided a reflective plate comprising a substrate, a plurality ofprotrusions each formed on the substrate and having a curved surface,and a reflective film formed on the substrate having the protrusions,wherein a shape of a frame line of each of the protrusions comprises abay-like curved line or a peninsula-like curved line.

[0047] In this configuration, a border line (frame line) between each ofthe protrusions and a portion (gap portion) in which each of theprotrusions is not formed can be pointed in various directions insteadof predetermined directions. This realizes preferable reflectiveproperties with high dispersion properties.

[0048] A planar shape of each of the protrusions may be indefinite, andat least a part of the gap portion between the protrusions may beprovided in a mesh-like pattern or indefinite pattern.

[0049] A frame line of each of the protrusions may form at least oneclosed curved-line, and when a tangent line drawn along the curved lineon the substrate is represented by an angle in which a predetermineddirection is taken to be 0 degrees, the angle may change from increaseto decrease or from decrease to increase at least three times when thecurved line is circled.

[0050] Moreover, at least one of frame lines of the protrusions may forman indefinite two-dimensional closed region having a curved line or astraight line.

[0051] Furthermore, a frame line of each of the protrusions may comprisea curved line angled with respect to the signal line or a straight lineangled with respect to the signal line.

[0052] In this configuration, the frame line of each of the protrusionscan be pointed in various directions. This realizes preferablereflective properties having high dispersion properties.

[0053] (Fabricating Method of Reflective Plate)

[0054] In order to solve the foregoing problems, there is provided amethod of fabricating a reflective plate, comprising: forming a layer ofa resin on a substrate, a plurality of column-shaped portions eachhaving a rectangle cross sectional shape by patterning the resin layerto be a predetermined shape so that a part of a surface of the substrateis exposed, imparting an affinity for the resin to the exposed part ofthe surface of the substrate by surface treatment, the exposed partbeing between the column-shaped portions, forming a plurality ofprotrusions each having a curved surface by heat treatment to theplurality of column-shaped portions so that the resin flows on theexposed part of the surface of the substrate, and forming a reflectivefilm at least on the protrusions.

[0055] The above-described configuration prevents the column-shapedportions' trying to cohere by their surface tension instead of flowingon the substrate even after heat treatment is conducted to thecolumn-shaped portions and thus the column-shaped portions are inreadiness for heat deformation. In other words, the exposed part of thesurface of the substrate between the column-shaped portions are given anaffinity for the resin before conducting heat treatment to thecolumn-shaped portions, so that the column-shaped portions can easilyflow on the substrate. As a result, a gap between the protrusions iskept from becoming wide in the step of forming the protrusions, and thusan increase in specularity is inhibited. Furthermore, even if there aretemperature variations on the substrate in the step of heat treatment,flowability variations of the resist on the surface of the substrate areinhibited. Thus, it is made possible to fabricate a reflective plateexcellent in dispersion properties with improved yields.

[0056] In addition, in the above-described configuration, it is notnecessary to provide another resin layer on the protrusions in order tohave a protrusion-depression shaped surface of the reflective film. Itis only necessary to form the protrusions to have theprotrusion-depression shaped surface of the reflective film having fewerflat portions. This makes it possible to fabricate a thin reflectiveplate. In addition, since the number of steps is smaller thanconventional fabricating methods, fabrication costs are reduced.

[0057] The step of imparting an affinity for resin to the exposed partof the surface of the substrate may be such that the exposed part of thesurface of the substrate comes into contact with one functional groupselected from functional groups shown in a general formula (1) below anda compound having a functional group that shows an affinity for theresin, so that a functional group having active hydrogen that exists onthe exposed part reacts to the functional group selected from thefunctional groups shown in the general formula (1) below in order toform a film made of the compound.

[0058] (In this formula, a symbol A denotes one atom selected from agroup consisting of silicon, germanium, tin, titanium, and zirconium. Asymbol X denotes one functional group selected from a group consistingof halogen, an alkoxy group, and an isocyanate group.)

[0059] The step of imparting an affinity may be such that the exposedpart of the surface of the substrate is irradiated by an ultravioletray.

[0060] In order to solve the foregoing problems, there is provided amethod of fabricating a reflective plate, comprising: forming a layer ofa resin on a substrate, a plurality of column-shaped portions eachhaving a rectangle cross sectional shape by patterning the layer of theresin to be a predetermined shape so that a part of a surface of thesubstrate is exposed, plasticizing the column-shaped portions byapplying a plasticizer on the column-shaped portions, forming aplurality of protrusions each having a curved surface by heat treatmentto the plurality of column-shaped portions so that the resin flows onthe exposed part of the surface of the substrate, and forming areflective film at least on the protrusions.

[0061] Because of variations in the heat properties of resin materials,they have variations in heat deformation temperature. In theabove-described method, even when using a resin to be heat-deformed at ahigh temperature, the plasticizer is applied on the column-shapedportions to plasticize them, and this reduces the heat deformationtemperature of the column-shaped portions. As a result, it is made easyfor the column-shaped portions to flow on the substrate.

[0062] In order to solve the foregoing problems, there is provided amethod of fabricating a reflective plate, comprising: forming a layer ofa resin on a substrate, a plurality of column-shaped portions eachhaving a rectangle cross sectional shape by patterning the layer of theresin to be a predetermined shape so that a part of a surface of thesubstrate is exposed, hardening surface layers of the column-shapedportions, forming a plurality of protrusions each having a curvedsurface by heat treatment to the plurality of column-shaped portions sothat the resin flows on the exposed part of the surface of thesubstrate, and forming a reflective film at least on the protrusions.

[0063] The above-described method is useful when the heat properties ofa resin show high flowability when the resin is in readiness for heatdeformation. In this method, hardening of the surface layers of thecolumn-shaped portions prevents an excessive flowage of the resin on thesubstrate. On the other hand, since the insides of the column-shapedportions inherently have flowability, the column-shaped portions areheat-deformed appropriately. This prevents the protrusions from bindingtogether caused by the absence of gaps therebetween, and makes itpossible to form a plurality of protrusions each having a predeterminedangle. As a result, uneven reflective brightness on the surface of thesubstrate is prevented, and a reflective plate with preferablereflective properties is fabricated with improved yields.

[0064] The step of hardening the surface layers of the column-shapedportions may be such that the column-shaped portions are irradiated byan ultraviolet ray having a dominant wavelength of 300 nm or less.

[0065] The step of hardening the surface layers of the column-shapedportions may be such that an alkaline solution is applied on thecolumn-shaped portions.

[0066] In addition, in order to solve the foregoing problems, there isprovided a method of fabricating a reflective plate having a gap portioncomprising a curved line and/or a broken line between a plurality ofprotrusions, the curved line and the broken line having a predeterminedwidth, comprising: forming a photosensitive resin layer on a substrate,light-exposing the photosensitive resin layer through a mask having apattern wherein a shape of a light shielding portion or a lighttransmitting portion comprises a curved line having a predeterminedwidth and/or a broken line having a predetermined width, forming aplurality of column-shaped portions by developing the light-exposedphotosensitive resin layer so that a part of a surface of the substrateis exposed, forming the plurality of protrusions each having a curvedsurface by heat treatment to the plurality of column-shaped portions,and forming a reflective film at least on the protrusions.

[0067] The above-described mask may have a pattern such that a width ofthe light shielding portion or the light transmitting portion is 3 μm orless.

[0068] In addition, in order to solve the foregoing problems, there isprovided a method of fabricating a reflective plate, comprising: forminga layer of a photosensitive resin on a substrate, light-exposing thelayer of the photosensitive resin through a mask having a lightshielding portion having a predetermined pattern or a light transmittingportion having a predetermined pattern, forming a plurality ofcolumn-shaped portions by developing the light-exposed photosensitiveresin layer so that a part of a surface of the substrate is exposed,imparting an affinity for the photosensitive resin to the exposed partof the surface of the substrate by heat treatment, the exposed partbeing between the column-shaped portions, forming a plurality ofprotrusions each having a curved surface by heat treatment to theplurality of column-shaped portions so that the photosensitive resinflows on the exposed part of the surface of the substrate, and forming areflective film at least on the protrusions, wherein, as the mask, sucha mask is used that a planar shape of the light shielding portion or thelight transmitting portion is non-circular, and when a frame line of theplanar shape of the light shielding portion or the light transmittingportion is divided into fine line segments, the line segments arepointed in all directions or in predetermined directions.

[0069] (Display Device)

[0070] The reflective plates described in the above configurations canbe applied to display devices such as reflective type liquid crystaldisplay devices and transflective type liquid crystal display devices.

[0071] Specifically, there is provided a display device comprising asubstrate having a plurality of nonlinear elements and wirings formed onthe substrate, a plurality of protrusions each formed on the substrateand having a curved surface, and a reflective film formed on thesubstrate having the protrusions, wherein a planar shape of each of theprotrusions is non-circular, and when a frame line of the planar shapeof each of the protrusions is divided into fine line segments, the linesegments are pointed in all directions or in predetermined directions.

[0072] In the above-described configuration, when the line segments arepointed in all directions, incident light from an arbitrary direction isdisplayed after reflected and diffused in various directions. This makesit possible to have a constant brightness of the display screen,irrespective of viewing directions. When the line segments are pointedin predetermined directions, it is possible that the display screen isbright only when the screen is viewed from predetermined directions.That is to say, the above-described configuration enables it to providea display device that provides appropriate reflective propertiesaccording to application.

[0073] In addition, in order to solve the foregoing problems, there isprovided another display device comprising a substrate having aplurality of nonlinear elements and wirings formed on the substrate, aplurality of protrusions each formed on the substrate and having acurved surface, and a reflective film formed on the substrate having theprotrusions, wherein a gap portion is provided between the protrusions,and a shape of the gap portion comprises a curved line having apredetermined width and/or a broken line having a predetermined width.

[0074] In this configuration, the occupancy area of the gap portion inthe surface of the substrate is minimized. This prevents an increase inreflected light in the regularly reflected direction and reduces theappearance of a light source on the display screen. In addition, sincethe protrusions have reflective properties excellent in dispersionproperties, it is made possible to provide a display device thatdisplays images with a constant brightness, irrespective of viewingdirections.

[0075] The above-described configuration may be such that, on thesubstrate, an auxiliary capacitor electrode electrically connected tothe nonlinear elements is provided, and, above the auxiliary capacitorelectrode, at least one of the protrusions is provided so that at leasta part of the gap portion overlaps with a periphery of the auxiliarycapacitor electrode.

[0076] A planar shape of the auxiliary capacitor electrode may bepolygonal having at least one reentrant angle. This prevents theprotrusion above the auxiliary capacitor electrode from becoming flat,and thus improves reflective properties.

[0077] The above-described configuration may be such that, on thesubstrate, an auxiliary capacitor electrode electrically connected tothe nonlinear elements is provided, and width of a gap portion above theauxiliary capacitor electrode is narrower than widths of other gapportions. This reduces the area of flat portions and thus improvesreflective properties.

[0078] The above-described configuration may be such that, on thesubstrate, an auxiliary capacitor electrode electrically connected tothe nonlinear elements is provided, and a maximum diameter of one ofprotrusions above the auxiliary capacitor electrode is narrower than amaximum diameter of a rest the protrusions.

[0079] The above-described configuration may be such that the substrateis light-transmissive, and the gap portion is not coated with thereflective film and is a light transmission region. This makes thedisplay device of the present invention a transflective type displaydevice.

[0080] In addition, in order to solve the foregoing problems, there isprovided another display device a substrate having a plurality ofnonlinear elements and wirings formed on the substrate, a plurality ofprotrusions each formed on the substrate and having a curved surface,and a reflective film formed on the substrate having the protrusions,wherein a shape of a frame line of each of the protrusions comprises abay-like curved line or a peninsula-like curved line.

[0081] In this configuration, a border line (frame line) between each ofthe protrusions and a portion (gap portion) in which each of theprotrusions is not provided is pointed in various directions instead ofpredetermined directions. This provides the border line with reflectiveproperties excellent in dispersion properties, making it possible toprovide a display device that displays images with a constantbrightness, irrespective of viewing directions.

[0082] The above-described configuration may be such that a planar shapeof each of the protrusions is indefinite, and at least a part of the gapportion between the protrusions is provided in a mesh-like pattern orindefinite pattern.

[0083] The above-described configuration may be such that a frame lineof each of the protrusions forms at least one closed curved-line, andwhen a tangent line drawn along the curved line on the substrate isrepresented by an angle in which a predetermined direction is taken tobe 0 degrees, the angle changes from increase to decrease or fromdecrease to increase at least three times when the curved line iscircled.

[0084] The above-described configuration may be such that at least oneof frame lines of each of the protrusions forms an indefinitetwo-dimensional closed region having a curved line or a straight line.

[0085] The above-described configuration may be such that a frame lineof each of the protrusions comprises a curved line or a straight linethat is angled with respect to the signal lines.

[0086] In this configuration, the frame line of each of the protrusionscan be pointed in various directions. This realizes good reflectiveproperties having high dispersion properties.

[0087] (Protrusion-Depression Structure)

[0088] In order to solve the foregoing problems, there is provided aprotrusion-depression structure comprising a substrate, a plurality ofprotrusions each formed on the substrate and having a curved surface,wherein a planar shape of each of the protrusions is non-circular, andwhen a frame line of the planar shape of each of the protrusions isdivided into fine line segments, the line segments are pointed in alldirections or in predetermined directions.

[0089] In the protrusion-depression structure having such aconfiguration, when the line segments are pointed in all directions, thestructure can be applied to reflective plates excellent in dispersionproperties. On the other hand, when the line segments are pointed inpredetermined directions, the structure can be applied to condensingplates that condense light into predetermined directions.

[0090] The protrusion-depression structure may be such that a gapportion is provided between the protrusions, and a shape of the gapportion comprises a curved line having a predetermined width and/or abroken line having a predetermined width.

[0091] The protrusion-depression structure may be such that a shape of aframe line of each of the protrusions comprises a bay-like curved lineor a peninsula-like curved line.

[0092] The protrusion-depression structure may be such that a planarshape of each of the protrusions is indefinite, and at least a part ofthe gap portion between the protrusions is provided in a mesh-likepattern or indefinite pattern.

[0093] The protrusion-depression structure may be such that a frame lineof each of the protrusions forms at least one closed curved-line, andwhen a tangent line drawn along the curved line on the substrate isrepresented by an angle in which a predetermined direction is taken tobe 0 degrees, the angle changes from increase to decrease or fromdecrease to increase at least three times when the curved line iscircled.

[0094] The protrusion-depression structure may be such that at least oneof frame lines of the protrusions forms an indefinite two-dimensionalclosed region having a curved line or a straight line.

BRIEF DESCRIPTION OF THE DRAWINGS

[0095]FIG. 1 is a graph showing the relationship between tilt angles ofprotrusions of a conventional reflective plate and the existenceprobability of the tilt angles.

[0096]FIG. 2 is a graph showing the relationship between an incidentangle (degree) of incident light in the reflective plate and theobtained gain.

[0097]FIG. 3A is a cross sectional view of protrusions after the step ofdevelopment to illustrate a method of fabricating a conventionalreflective plate, and FIG. 3B is a cross sectional view of theprotrusions after the step of heat fusion to illustrate a method offabricating the reflective plate.

[0098]FIG. 4A is a schematic plan view of another conventionalreflective plate, and FIG. 4B is a cross sectional view taken along theline A-A shown in FIG. 4A.

[0099]FIG. 5A is a schematic plan view of another conventionalreflective plate, and FIG. 5B is a cross sectional view taken along theline B-B shown in FIG. 5A.

[0100]FIG. 6A is a plan view of a reflective plate of Embodiment 1 ofthe present invention, FIG. 6B is a plan view showing the essential partof the reflective plate, and FIG. 6C is a plan view showing theessential part of a conventional reflective plate.

[0101]FIG. 7 is a view illustrating a contact angle and a tilt angle ofa protrusion of Embodiment 1.

[0102] FIGS. 8A-8E are cross sectional views illustrating a method offabricating the reflective plate of Embodiment 1 of the presentinvention.

[0103]FIG. 9A is a plan view schematically showing a photo-mask used inthe process of fabricating a conventional reflective plate, and FIG. 9Bis a plan view schematically showing a photo-mask used in the process offabricating the reflective plate of Embodiment 1.

[0104]FIG. 10 is a graph showing the relationship between tilt angles ofprotrusions of the reflective plate and the existence probability of thetilt angles.

[0105] FIGS. 11A-11F are views illustrating the process of fabricatingthe reflective plate.

[0106]FIG. 12 is a graph showing the relationship between an incidentangle of incident light in the reflective plate and the obtained gain.

[0107]FIG. 13 is a cross sectional view showing a reflective type liquidcrystal display device of Embodiment 2.

[0108]FIG. 14A is a schematic cross sectional view of a part of aprotrusion above an auxiliary capacitor electrode, and FIG. 14B is aschematic cross sectional view of the rest part of the protrusionoutside the region in which the auxiliary capacitor electrode isprovided.

[0109]FIG. 15 is a plan view of the protrusion provided above theauxiliary capacitor electrode.

[0110]FIG. 16 is a plan view of the protrusion, and a schematic crosssectional view of the protrusion taken along the line X-Y.

[0111]FIG. 17 is a plan view of another auxiliary capacitor electrode ofthe present embodiment.

[0112] FIGS. 18A-18G are views illustrating the process of fabricating areflective plate of Embodiment 8.

[0113]FIG. 19 is a plan view showing the essential part of a photo-maskused in Embodiment 8.

[0114]FIG. 20 is a plan view of a reflective plate of Embodiment 10.

[0115]FIG. 21 is a graph showing the relationship between tilt angles(degree) of protrusions of the reflective plate and the existenceprobability (%) of the tilt angles.

[0116]FIG. 22 is a plan view showing the essential part of a photo-maskused in Embodiment 10.

[0117]FIG. 23 is a plan view of a protrusion of a reflective type liquidcrystal display device of Embodiment 12 of the present invention.

[0118]FIG. 24 is a graph showing the relationship between tilt angles ofprotrusions and the existence probability of the tilt angles.

[0119]FIG. 25 is a graph showing the relationship between a contactangle of a protrusion and the integral value (area A) of the existenceprobability of the contact angle when tilt angles are in the range of 5to 10 degrees.

[0120]FIG. 26 is a graph showing the relationship between the maximumdiameter (μm) of a protrusion and its existence probability when tiltangles are in the range of 5 to 10 degrees.

[0121]FIG. 27 is a plan view of a protrusion of a reflective type liquidcrystal display device of Embodiment 12 of the present invention.

[0122]FIG. 28 is a cross sectional view of the reflective type liquidcrystal display device take along the line A-A shown in FIG. 27.

[0123]FIG. 29 is a cross sectional view schematically showing the wayincident light comes into a reflective type liquid crystal displaydevice and then is reflected.

[0124]FIG. 30 is a plan view showing the height of a protrusion ofEmbodiment 13 from the surface of a substrate using contour lines.

[0125]FIG. 31 is a plan view showing incident light a, b, and c incomingalong the line A-A from the left (as viewed in FIG. 31), and showing thedirection of movement of reflected light a′, b′, and c′.

[0126]FIG. 32 is a schematic cross sectional view showing incident lightd, e, and f and the direction of movement of reflected light d′, e′, andf′.

[0127]FIG. 33 is a plan view showing incident light d, e, and f incomingalong the line B-B from the left (as viewed in FIG. 33), and showing thedirection of movement of reflected light d′, e′, and f′.

[0128]FIG. 34 is an enlarged plan view showing the protrusion and a gapportion.

[0129]FIG. 35 is a plan view of the protrusion of Embodiment 13.

[0130]FIG. 36 is a plan view of other protrusions of Embodiment 13.

[0131]FIG. 37 is a plan view of still other protrusions of Embodiment13.

[0132] FIGS. 38A-38F are cross sectional views showing the process offabricating a reflective plate of Embodiment 13.

[0133]FIG. 39 is a cross sectional view of a pixel region of atransflective type liquid crystal display device of Embodiment 14.

[0134]FIG. 40 is a cross sectional view taken along the line J-J′ shownin FIG. 39.

[0135]FIG. 41 is a plan view of a protrusion of Embodiment 15 of thepresent invention.

[0136]FIG. 42 is a cross sectional view taken along the line K-K′ shownin FIG. 41.

[0137]FIG. 43 is a plan view of protrusions of Embodiment 16 of thepresent invention.

[0138]FIG. 44 is a plan view of other protrusions of the presentinvention.

[0139]FIG. 45 is a plan view of protrusions of Embodiment 17 of thepresent invention.

[0140]FIG. 46 is a plan view of a transflective type liquid crystaldisplay device of Embodiment 17.

[0141]FIG. 47 is a plan view schematically showing the regular spiralalignment of protrusions of Embodiment 18 of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0142] Embodiment 1

[0143] An embodiment of the present invention will be described below.

[0144]FIG. 6A is a plan view of a reflective plate of the presentembodiment. FIG. 6B is a plan view showing the essential part of thereflective plate. FIG. 6C is a plan view showing the essential part of aconventional reflective plate. FIG. 7 is a view schematically showing aprotrusion of the reflective plate.

[0145] As shown in FIG. 6A, a reflective plate 201 is composed of asubstrate, a plurality of protrusions 202, and a reflective filmprovided to cover the protrusions 202 on the substrate.

[0146] As the substrate, an insulative material such as a glass may beused, for example.

[0147] Each of the protrusions 202 has a smooth curved surface, anon-circular shape, and an indefinitely planar shape. Also, theprotrusions 202 are randomly disposed on the substrate and independentof one another. This prevents light interference caused by a repeatedpattern in which the protrusions 202 are regularly aligned, and alsoprevents the coloring of incident light. In addition, more than twotypes of the planar shapes of the protrusions 202 are combined andrandomly disposed by turning them around. Between a protrusion 202 and aprotrusion 202, a gap portion 203 which is an exposed part of thesurface of the substrate is formed. The gap portion 203 comprises acurved line and/or a broken line, both having a predetermined width.

[0148] A contour line 207 of each of the protrusions 202 is aboutidentical to the shape of a border line (frame line) 204 between each ofthe protrusions 202 and the gap portion 203 in which each of theprotrusions 202 is not provided. Corners of each of the protrusions 202are smoothly heat-deformed along the frame line 204, and therefore thedirection of the curved surface of each of the protrusions 202 dependson the frame line 204.

[0149] The planar shape of each of the protrusions 202 is notparticularly limited. However, macroscopically, the shape is designedsuch that the ratio between the maximum length W₁ of a direction X (alateral direction of the display screen) and the maximum length L₁ of adirection Y (a longitudinal direction of the display screen) is 1:1(FIG. 6A). Reasons for making the planar shape of each of theprotrusions 202 non-circular and indefinite are as follows.

[0150] If the planar shape of a protrusion 205 is circular as shown inFIG. 6C, the reflective plate shows ideal reflective properties when itis desired that light be reflected and diffused (dispersed) in alldirections. However, when the circular protrusion 205 is plurallyprovided on the substrate, a flat gap portion 206 which is relativelylarge in area is formed between protrusions 205 no matter how denselythe protrusions 205 are disposed. Contrarily, when the planar shape ofeach of the protrusions are indefinite as in the present embodiment, theshape of a gap portion 203 comprises a curved line having apredetermined width and/or a broken line having a predetermined width.In other words, the area of the flat gap portion is minimized. Thisreduces the regular reflection of light and inhibits the appearance of alight source on the display screen.

[0151] In addition to the prevention of regular reflection of light, theplanar shape of each of the protrusions 202 is controlled for animprovement in dispersion properties. This is specifically describedsuch that, as shown in FIG. 6B, the frame line 204 of the protrusion 205is divided into fine line segments 204 a, 204 b, 204 c, and the like.The line segments 204 a, 204 b, 204 c, and the like are determined toapproximately point uniformly in all directions instead of only incertain directions. When the fine line segments of the frame line arepointed in all directions, it is possible to have almost the same lightdiffusion properties as when the planar shape of the protrusion iscircular. That is to say, the reflective plate of the present inventionimproves its uniform diffusion properties and disperses reflected lightin all directions to have a constant brightness, irrespective of viewingdirections.

[0152] It is to be noted that each of the line segments 204 a, 204 b,204 c, and the like is a divided segment that has enough length to berecognized as a straight line. This is because if a line segment isrecognized as a straight line, its direction can be determined. Sincethe protrusions 202 are formed by exposure using a mask, the length ofeach of the line segments is determined according to exposure limits.Specifically, it is impossible to form a curved line with a length ofless than 1 μm by patterning in the step of mask exposure. Therefore,when the protrusions 202 are formed by mask exposure, the frame line 204is divided into line segments each with a length of about 1 μm so thateach of the line segments is recognized as an approximate straight line.That is to say, the line segments 204 a, 204 b, 204 c, and the like areobtained by dividing the frame line 204 every 1 μm.

[0153] The height H (μm) of each of the protrusions 202 is preferably inthe range of 1.2-4 μm when the reflective plate is applied to liquidcrystal display devices and a cell gap is in the range of 3-10 μm. Inaddition, the contact angle θ of each of the protrusions 202 ispreferably in the range of 10-25 degrees. It is to be noted that thecontact angle is an angle formed by the substrate and the surface ofeach of the protrusions 202 at a contact line (FIG. 7).

[0154] In each of the protrusions 202, the approximate ratio between themaximum length L₁ of a direction Y (a longitudinal direction of thedisplay screen) and the maximum length W₁ of a direction X (a lateraldirection of the display screen) is 1:1. In addition, the maximumdiameter φ (μm) of each of the protrusions 202 is preferably in therange of 15-40 μm. A maximum diameter φ of less than 15 μm causesinconvenience because the contact angle becomes large when the height ofeach of the protrusions 202 is 1.2 μm or more. Also, the maximumdiameter φ of more than 40 μm causes inconvenience because, when filmthickness is 4.0 μm or less, the planar shape of each of the protrusions202 becomes trapezoidal and the top of each of the protrusions 202becomes flat.

[0155] The maximum diameter of each of the protrusions 202 is preferablyfrom 5 to 20 times larger than the height of each of the protrusions202. In addition, the protrusions 202 are preferably disposed 30 or lessper area of 1×10⁴ μm². When more than 30 of the protrusions 202 aredisposed, the protrusions 202 start to have regularity in disposition,ending up with a repeated pattern. This causes light interference, andthe coloring of reflected light is recognized, which is not preferable.In addition, when a TFT, a contact hole, and the like are required to beprovided in one pixel, it is difficult to form the protrusions 202independently of one another, if more than 30 of the protrusions 202 aredisposed.

[0156] The width of the gap portion 203 is preferably from 1 to 10 μm,more preferably, it is in the range of 2-10 μm, and ever morepreferably, it is in the range of 4-8 μm. The minimum width of the gapportion 203 is determined by exposure limits. On the other hand, whenthe width of the gap portion 203 is more than 10 μm, such inconvenienceoccurs as an increase in light to be regularly reflected and theappearance of a light source on the display screen.

[0157] The width of the gap portion 203 needs to be at least 1 μm, inconsideration of temperature distribution in the step of heat treatmentand the amount of heat deformation affected by the shape of the gapportion. When the area of the gap portion 203 is made large, theproportion of the flat portion increases. Therefore, to have arelatively small effect of the gap portion 203, the width of each of theprotrusions 202 is made large. Specifically, when the maximum width ofeach of the protrusions 202 is more than 5 times larger than the widthof the gap portion 203, the proportion of the flat portion decreases.However, when the maximum width of each of the protrusions 202 is morethan 50 times larger than the width of the gap portion 203, the top ofeach of the protrusions 202 becomes flat and the distribution of smalltilt angles increases. Therefore, the maximum width of each of theprotrusions 202 is from 5 to 50 times larger than the width of the gapportion 203.

[0158] The reflective plate of the present embodiment is fabricated inthe following manner.

[0159] FIGS. 8A-8B illustrate the process of fabricating the reflectivefilm of the present embodiment. FIG. 9A is a plan view schematicallyshowing a photo-mask used in the process of fabricating a conventionalreflective plate. FIG. 9B is a plan view schematically showing aphoto-mask used in the process of fabricating the reflective plate ofthe present embodiment. FIG. 10 is a graph showing the relationshipbetween tilt angles of protrusions of the reflective plate and theexistence probability of the angles.

[0160] First, as shown in FIG. 8A, an acrylic p-type photo-resist (brandname: PC403, available from J.S.R.) is spin-coated on a glass substrate211 to form a resist layer (resin layer) 212. In forming the resistlayer 212, a printing method, a dip method, and the like may be usedother than a spin coating method. The thickness of the resist layer 212is made 2 μm, for example. This resist layer 212 is pre-baked on a hotplate for 2 minutes at 90° C.

[0161] Next, as shown in FIG. 8B, the resist layer 212 is light-exposedthrough a photo-mask 131. The photo-mask 131 has such a pattern thatlight shielding portions made of Cr are unevenly disposed as shown inFIG. 9A. The planar shape of each of the light shielding portions is ahexagon with a diameter of 7 μm. In addition, a gap between the lightshielding portions 132 is in the range of 4 μm or less. It is to benoted that, although the mask having a pattern of the hexagonal lightshielding portions is used as the photo-mask 131, the present inventionis not limited to this, insofaras the planar shape of each of the lightshielding portions does not have shape anisotropy in a specificdirection. Specifically, a shape close to a circle such as a dodecagonmay be employed.

[0162] Subsequently, the light-exposed resist layer 212 is developed toform a plurality of resist columns (column-shaped portions) 214 on thesubstrate 211. The height of each of the resist columns is approximatelyequal because they are developed at approximately the same speed. Inthis development, for example, NMD-3 (brand name), a developer availablefrom Tokyo Ohka Kogyo Co., Ltd. may be used.

[0163] In a conventional fabricating method, the resist columns 214 wereprocessed at 150° C. in the step of heat treatment. Thereby, as shown inFIG. 8D, corners of the tip of each of the resist columns 214 areheat-deformed so that the protrusions 202 each having a smooth curvedsurface are formed. In addition, to cover the protrusions 202, Al isdeposited over the glass substrate 211 to form a reflective film 216(FIG. 8E). Al may be formed by a sputtering method other thandepositing. Other than Al, a reflective material may be Ag, Ni, or Ti,and also may be an alloy of Al/Ta and the like.

[0164] However, when the tilt angle distribution of the protrusions 202formed by the conventional fabricating method was examined, suchdistribution was obtained as shown as a curved line (b) in FIG. 10. Areason for the high existence probability of tilt angles near 0 degreesis that gaps between the protrusions 202 were not sufficiently filledduring heat deformation.

[0165] In view of this, a photo-resist material having high meltingproperties (flowability at the time of heat deformation) was used sothat the photo-resist could flow between the resist columns 214. As aresult, the existence probability of tilt angles near 0 degrees wasreduced. However, when the gaps between the resist columns 214 were 3 μmor more, it was impossible to fill the gaps sufficiently only by heatfusion. This is presumably because there is a low affinity between theglass substrate 211 and the photo-resist. In addition, because of thelow affinity, the photo-resist with flowability does not expand on thesurface of the glass substrate, but extends in the thickness directionbecause of the surface tension of the photo-resist. As a result, thetilt angle of each of the obtained protrusions 202 became more than 13degrees, which was high.

[0166] In order for the reflective plate to have an ideal reflectivesurface, it is preferable that the tilt angle distribution of theprotrusions 202 is 8 degrees or less as shown as a solid line (a) inFIG. 10. When the tilt angle is more than 8 degrees, light that has comeinto a liquid crystal panel is reflected outside to draw an angle ofhigh degrees, making it impossible to utilize the light as displaylight. Or else, the light is confined within the display panel and cannot go outside. As a result, even if the protrusions are provided on thereflective plate, the protrusions do not effectively function to enhancereflective brightness. It is to be noted that the tilt angle is an angleformed by a tangent line that contacts with each of the protrusions 202at a contact point P and the surface of the substrate as shown in FIG.7.

[0167] Thus, to make the tilt angle of each of the protrusions 8 degreesor less and reduce the flat portion, it is necessary to do thefollowing: Use a mask with such a pattern that gaps between theprotrusions are each designed to be 3 μm or less; Reform the surface ofthe substrate so that the heat-fused photo-resist can easily flow on thesubstrate; Transform the photo-resist into a state to easily flow on thesubstrate.

[0168] In the conventional method of fabricating the reflective film,such a photo-mask 131 was used as to have a pattern in which the lightshielding portions 132 each having a predetermined shape (hexagonal, forexample) were randomly disposed. When using such a pattern, the disposedlight shielding portions 132 are almost fully dense. Such a regularpattern causes a strong light interference and the coloring of thereflective plate.

[0169] In view of this, in the present embodiment, a photo-mask 221shown in FIG. 9B is used in the step of exposure. The photo-mask 221 iscomposed of light shielding portions 222 each having an indefiniteplanar shape and light transmitting portions 223 provided between thelight shielding portions 222. The light shielding portions 222 areprovided randomly. The width of each of the light transmitting portions223 is set to be 3 μm or less. The light transmitting portions 223 donot necessarily have a uniform width, which are determined appropriatelyaccording to the width of each of gaps between the protrusions of thereflective plate. The width of each of the light transmitting portions223 is preferably 3 μm or less, and more preferably, it is from 1 to 2μm.

[0170] Even a photo-resist that shows high flowability when it isheat-deformed does not expand only by heating. Therefore, if the widthbetween the developed resist columns is 3 μm or more, the proportion ofthe flat portion increases. In addition, the width of each of the lighttransmitting portions is preferably 2 μm or less, considering that theexposure of the photo-resist might extend off the pattern of thephoto-mask depending on exposure conditions, or the photo-resist mightreduce its thickness in the step of development. As a result, gaps 213between the resist columns 214 are reliably filled the by heat fusion.On the other hand, if the width of each of the light transmittingportions 223 is too small, the resist columns may not be sufficientlydistant from one another depending on exposure and developmentconditions. Therefore, the width of each of the light transmittingportions 223 is preferably 1 μm or more.

[0171] Furthermore, in the pattern of the photo-mask, the widths of thegaps may be a mixture of two or more types of widths, for example, 1 μmand 2 μm. This further reduces light interference in the obtainedreflective plate. In addition, two or more types of the shapes of thelight shielding portions (or light transmitting portions) may becombined and randomly disposed by turning them around. This reduces thecoloring of the reflective plate. It is to be noted that the tilt angledistribution of the reflective plate can be preferably designed also byselecting the shapes and sizes of the light shielding portions. However,since the surface of each of the light shielding portions is required tobe provided with a tilt angle by heat fusion, each of the lightshielding portions is limited in area or shape. Therefore, it is notpreferable to make the light shielding portions too large in area.

[0172] Embodiment 2

[0173] In the present embodiment, a method of fabricating a reflectiveplate different from Embodiment 1 will be described.

[0174] The method of fabricating a reflective film of the presentembodiment is different from that of Embodiment 1 in that the surface ofthe substrate is reformed so that the heat-fused photo-resist can easilyflow on the substrate. This is detailed as follows.

[0175] FIGS. 11A-11F illustrate the process of fabricating thereflective plate of the present embodiment.

[0176] First, similarly to Embodiment 1, a p-type photo-resist (acrylicresin, brand name: PC403, available from J.S.R.) is spin-coated on aglass substrate 211 to form a resist layer 212 (FIG. 11A).

[0177] Next, as shown in FIG. 11B, the resist layer 212 is light-exposedthrough a photo-mask 221.

[0178] Subsequently, the light-exposed resist layer 212 is developed toform a plurality of resist columns 214 on the substrate 211 as shown inFIG. 11C.

[0179] After the development, as shown in FIG. 11D, a treatment agent224 which enhances the affinity of the substrate for the photo-resist iscoated over the substrate, which has the plurality of resist columns 214(a gap between a resist column 214 and a resist column 214 is about 4μm).

[0180] The treatment agent 224 comprises a compound having at least onefunctional group selected from functional groups shown as a generalformula (1) below.

[0181] (In this formula, a symbol A denotes one atom selected from thegroup consisting of silicon, germanium, tin, titanium, and zirconium. Asymbol X denotes one functional group selected from the groupsconsisting of halogen, an alkoxy group, and an isocyanate group.)

[0182] In addition, to enhance an affinity for the photo-resist, thecompound has an affinity group such as a methyl group. If a treatmentagent 217 is coated over the substrate 211, in gaps between the resistcolumns 214, the surface energy of the exposed part of the surface ofthe substrate changes.

[0183] The surface energy changes in the following manner. When afunctional group represented by general formula (1) of the compoundreacts to an OH group on the surface of the substrate, HX is removed andthe compound is chemically absorbed to the surface of the substrate. Asa result, a film is formed on the surface of the substrate at the gaps.On the other hand, since the compound absorbed to the surface of thesubstrate has an affinity group which shows an affinity for thephoto-resist, the surface energy of the surface of the substratechanges.

[0184] The treatment agent 224 may be, for example, hexamethyldisilazane(trade name: OAP, available from Tokyo Ohka Kogyo Co., Ltd.),methyltrichlorosilane, or cyclohexyltrichlorosilane.

[0185] After coating the treatment agent 224, heat treatment isconducted to the resist columns 214 to form the protrusions 202 whosetips are roundly curved as shown in FIG. 11E. The gaps between theresist columns 214, which are the exposed parts of the surface of thesubstrate 211, have an enhanced affinity for the photo-resist. Thisenables the heat-fused photo-resist to flow and expand on the substrate211 to fill the gaps. As a result, the gaps each having a width of about4 μm are filled and the tilt angle of each of the protrusions 202 ismade small, realizing almost ideal tilt angle distribution.

[0186] Finally, Al was deposited over the substrate 211 having thereonthe plurality of protrusions 202 to form a reflective film 225 as shownin FIG. 11F. Other than depositing, a sputtering method may be used informing the reflective film 225 using Al. In addition, other than Al, areflective film material may be Ag, Ni, or Ti, and also may be an alloyof Al and Ta and the like.

[0187] If the reflective plate is fabricated in the above-describedmethod, the resist columns 214 having the same volume are deformed byheat fusion. This enables it to form the protrusions in which tiltangles are controlled with good reproducibility only by setting heattreatment temperature. Furthermore, in the conventional method in whichthe development of the resist is stopped halfway so that the resistlayer remains between the resist columns. However, in the presentembodiment, parts of the resist layer that need to be removed arecompletely removed. Therefore, it is not necessary to precisely controlconditions of exposure and development, insofaras such a condition issatisfied that parts of the resist layer that need to be removed arecompletely removed. That is to say, conditions of the fabrication of thereflective plate are relaxed.

[0188] In the reflective plate thus obtained, tilt angle distributionand reflective properties were studied. Tilt angle distribution wasalmost ideal as shown in FIG. 10 as a curved line (c). Reflectiveproperties were studied in the following manner. A transparent layerhaving the same light transmissivity as a liquid crystal layer wasprovided on the reflective plate, and an ND filter having a 0.1 OD valuewas disposed on the transparent layer. Then, dispersion strength wasmeasured when an incident angle of incident light with respect to thereflective plate is 0 degrees, that is, incident light comes in from thefront of the reflective plate. The results are shown in FIG. 12. FIG. 12is a graph showing the relationship between an incident angle and theobtained gain. It was recognized that the reflective plate of thepresent embodiment showed such reflective properties as shown as acurved line (a). Specifically, in the reflective properties shown as thecurved line (a), gain showed more than a constant value when theincident angle was from minus 25 to 25 degrees, where the reflectiveplate reflects light brightly. It is to be noted that gain shown in FIG.12 is a ratio when BaSO₄ reflective strength is taken to be 1.

[0189] For reference, the reflective properties of the conventionalreflective plate described in Embodiment 1 are also shown in FIG. 12 (acurved line (b)). In the reflective properties shown as the curved line(b), high gain was recognized in the regularly reflected direction,which led to brightness. However, gain was extremely low in otherranges, which led to darkness. In addition, although the conventionalreflective plate is brighter than that of the present embodiment whenthe incident angle was around ±40 degrees, there were no visual effectson the conventional reflective plate because it had inherently low gainat ±40 degrees.

[0190] The reflective plate of the present embodiment can be applied toreflective type liquid crystal display devices. FIG. 13 is a crosssectional view of a reflective type liquid crystal display device of thepresent embodiment.

[0191] As shown in FIG. 13, the reflective type liquid crystal displaydevice comprises a substrate 211, a counter substrate 226 (displayscreen side), and a liquid crystal layer 227 sandwiched between thesubstrate 211 and the counter substrate 226.

[0192] In the reflective plate of the present embodiment, the substrate211 further comprises, TFTs and an alignment film and the like (notshown). A reflective film 215 also has a function as a pixel electrode.

[0193] On the inside of the counter substrate 226, a color filter 228 isprovided. On the inside of the color filter 228, a transparent electrode229 made of indium tin oxide (ITO) is provided. In addition, the countersubstrate 226 is light-transmissive, and the liquid crystal layer 227contains a predetermined liquid crystal material.

[0194] The reflective type liquid crystal display devices having theabove-described configuration are in demand in the market of cellularphones and compact personal computers. However, since reflectiveproperties required of each product are different, it is impossible toapply reflective type liquid crystal display devices having the samereflective properties uniformly to all products. For example, a cellularphone is free to change the angle of its display screen, and thereforeneeds to have high brightness rather than a wide viewing angle. On theother hand, like the display screen of a personal computer, a wideviewing angle is a necessary condition for a wide display screen.Therefore, the tilt angle distribution of the reflective surface needsto be redesigned according to application. These requirements resultingfrom product performance are effectively dealt with by the reflectivetype liquid crystal display device of the present embodiment, in whichtilt angle distribution can be changed by adjusting the thickness of theresist layer and the size of each of the protrusions at the time offorming the protrusions.

[0195] In the present embodiment, the direct coating of OAP on thesubstrate was described as the step of imparting an affinity to thesubstrate. However, the present embodiment is not limited to this, andfor example, it is possible to put the substrate 211 in vapor phase OAP.

[0196] Embodiment 3

[0197] A method of fabricating a reflective plate of the presentembodiment is different from the method of fabricating the reflectiveplate of Embodiment 2 in that the surface of the substrate is exposed byan ultraviolet ray to soften the photo-resist and improve the affinitybetween the surface of the substrate and the photo-resist.

[0198] Specifically, the exposure of an ultraviolet ray breaks thecrosslinked structure of the photo-resist so that the photo-resistlowers its heat deformation temperature. This enables higher flowabilityof the photo-resist when it is ready for heat deformation, compared witha photo-resist that is not exposed by an ultraviolet ray. In addition,since the exposure of an ultraviolet ray removes residues of thephoto-resist between the resist columns, the affinity between thesubstrate and the photo-resist improves. As a result, the photo-resistcan easily flow on the substrate in the step of heat treatment, makingit possible to fabricate a reflective plate having preferable reflectiveproperties.

[0199] It is preferable that an ultraviolet ray to be exposed to thephoto-resist has a wavelength within a predetermined range, and the peakof the wavelength is around 365 nm. In addition, if the amount of anultraviolet ray is enhanced to about 300 mJ/cm², the photo-resist can bediscolored.

[0200] Embodiment 4

[0201] A method of fabricating a reflective plate of the presentembodiment is different from the method of fabricating the reflectiveplate of Embodiment 2 in that a surfactant is used in place of OAP.

[0202] When a surfactant is coated over the substrate after the step ofdevelopment, the surface energy of the surface of the substrate isreduced, making it possible to improve the affinity between the surfaceof the substrate and the photo-resist. When the resist-columns areheat-fused and their flowability is enhanced, the photo-resist promotesits spreading-wetting. As a result, gaps each having a width of 3 μmbetween the resist columns are filled.

[0203] The surfactant may be, for example, dioctyl-sulfosuccinate-sodiumor butylnaphthalene-sulfonate-sodium.

[0204] Embodiment 5

[0205] A method of fabricating a reflective plate of the presentembodiment is different from the method of fabricating the reflectiveplate of Embodiment 2 in that, instead of using OAP, the substrate isimmersed in a solvent of the photo-resist.

[0206] The photo-resist is inherently soluble to the solvent. Therefore,when the photo-resist is in readiness for heat deformation, the surfacelayers of the resist-columns flow more easily on the surface of thesubstrate.

[0207] The solvent may be, for example, a solvent of the photo-resistsuch as diethylene glycol-ethyl-methyl-ether, ethyl-cellosolveacetate,or methyl-isobutyl-ketone.

[0208] The method of putting the solvent on the substrate includesimmersion, spraying, and a method in which the substrate is disposed inan air-tight vessel having therein a solvent vapor.

[0209] Embodiment 6

[0210] In the present embodiment, the protrusions are also providedabove an auxiliary capacitor electrode which is electrically connectedto a TFT element (nonlinear element). When the width of each of thelight shielding portions (or light transmitting portions) of thephoto-mask was set to be uniformly 5 μm, the width of a part of a gapportion above the auxiliary capacitor electrode was 6 μm, showing atendency to be wider than the rest part of the gap portion in otherregions, which had a width of 4.5 μm. This is because a titanium layeris provided as the auxiliary capacitor electrode below the lightshielding portions in the step of exposure. Specifically, since thetitanium layer reflects exposure light, a region above the titaniumlayer is exposed more than other regions. As a result, it is presumedthat the amount of development increased in the region above thetitanium layer, thus widening the width of the part of the gap portionabove the titanium layer.

[0211] In view of this, in a region of the pattern of the photo-maskthat correspondeds to the auxiliary capacitor electrode, the width ofthe light shielding portion (or light transmitting portion) was madenarrow to about 3 μm. As a result, the width of the part of the gapportion above the auxiliary capacitor electrode became 4 μm, making itpossible to reduce a flat portion. This further improved dispersionproperties.

[0212] Concerning to the shape of each of the protrusions, a comparisonwas conducted between a protrusion among the protrusions above theauxiliary capacitor electrode and the rest of the protrusions in otherregions. As shown in FIG. 14A, a top portion 232 of a protrusion 231above the auxiliary capacitor electrode was flat. On the other hand, aprotrusion 233 in other regions was smoothly curved and had no flatregions as shown in FIG. 14B. In view of this, the maximum diameter ofthe part of the protrusion above the auxiliary capacitor electrode wasmade small from 30 μm to 25 μm. This enabled to prevent the top portionfrom becoming flat.

[0213] As the auxiliary capacitor electrode, titanium, molybdenum,aluminum, and the like may be used. Since these materials have differentlight reflectivity, the photo-mask needs to be designed according toeach of their reflectivity. However, the use of any of these materialscan not prevent an increase in the amount of exposure in the regionwhere the auxiliary capacitor electrode is provided. Accordingly, toform a protrusion that is shaped for preferable reflective properties,the maximum diameter of a part of the protrusion is made smaller thanthat of the rest part of the protrusion in other regions, and the widthof a part of a gap portion is made narrower than that of the rest partof the gap portion in other regions.

[0214] Embodiment 7

[0215] In the present embodiment, one of the protrusions is providedabove the auxiliary capacitor electrode so that at least a part of thegap portion overlaps with the periphery of the auxiliary capacitorelectrode. FIG. 15 is a plan view of a protrusion provided above theauxiliary capacitor electrode. FIG. 16 is a plan view of the protrusion,and a schematic cross sectional view of the protrusion taken along theline X-Y. FIG. 17 is a plan view of another auxiliary capacitorelectrode of the present embodiment.

[0216] As shown in FIG. 15, an auxiliary capacitor electrode 243 isprovided to cover a signal line 244 through an insulative layer in orderto form an auxiliary capacitor. The auxiliary capacitor electrode 243 iselectrically connected to a TFT element (nonlinear element), which isnot shown.

[0217] Above the auxiliary capacitor electrode 243, a protrusion 241 isprovided. The protrusion 241 has two tip portions 245-246 as shown inFIG. 16. A gap portion 242 formed between the protrusion 241 and anotherprotrusion is provided along the periphery of the auxiliary capacitorelectrode 243.

[0218] The auxiliary capacitor electrode 243 is a polygon that lookslike a combination of two polygons and has a reentrant angle in acertain portion. If the planar shape of the auxiliary capacitorelectrode is quadrangular, the top of the protrusion formed above theauxiliary capacitor electrode becomes. flat. In the step of exposure,since the auxiliary capacitor electrode reflects exposure light, aregion above the electrode is exposed more than other regions. If theplanar shape of the auxiliary capacitor electrode is quadrangular, theamount of exposure uniformly increases in the region above theelectrode. As a result, the top of the protrusion becomes flat, and theobtained protrusion has strong specularity.

[0219] However, in the present embodiment, the planar shape of theauxiliary capacitor electrode 243 has a reentrant angle, and the gapportion 242 is provided at the periphery of the electrode 243. Thisenables it to vary the height of the protrusion between the reentrantangle and a protruding angle, because the volume of the photo-resistvaries between the reentrant angle and the protruding angle. As aresult, the tip portions 245-246 are formed as shown in FIG. 16, makingit possible to improve dispersion properties even above the auxiliarycapacitor electrode 243.

[0220] In the above-described configuration, even if the cell gap issmall, it is possible to keep the cell gap uniform throughout thesubstrate without forming a flat surface on the protrusion.

[0221] Specifically, when the protrusion is provided above the auxiliarycapacitor electrode that is formed on a position higher than otherportions in a direction perpendicular to the surface of the substrate,there appears a large difference in height between the protrusion andprotrusions in other regions. This makes the cell gap uneven. On theother hand, when a low protrusion is provided above the auxiliarycapacitor electrode, a flat surface is widened on the protrusion,resulting in strong specularity. However, in the reflective plate of thepresent embodiment, even if a low protrusion is provided, no flatsurface is formed thereon. In addition, height difference between theprotrusion and protrusions in other regions is not made large.

[0222] In addition, as shown in FIG. 17, an opening portion 252 may beprovided inside an auxiliary capacitor electrode 251. A gap portion 253is provided at the periphery of an auxiliary capacitor electrode 251. Inthis configuration, the protrusion is depressed towards the auxiliarycapacitor electrode 251, and consequently, a curved surface is formed onthe protrusion provided above the auxiliary capacitor electrode 251.This enables to further reduce a flat surface.

[0223] Embodiment 8

[0224] A method of fabricating a reflective plate of the presentembodiment will be described below.

[0225] A method of fabricating the reflective plate of the presentembodiment is different from the method of fabricating the reflectiveplate of Embodiment 1 in that the surface of the substrate is reformedso that the heat-fused photo-resist can easily flow on the substrate.This is detailed as follows.

[0226] FIGS. 18A-18G illustrate the fabricating process of a reflectiveplate of the present embodiment.

[0227] First, as shown in FIG. 18A, a p-type photo-resist (acrylicresin, brand name: PC403, available from J.S.R.) is spin-coated on aglass substrate 301 to form a resist layer (resin layer) 302. In formingthe resist layer 302, a printing method, a dip method, and the like maybe used other than a spin coating method. The thickness of the resistlayer 302 is made 2 μm, for example. This resist layer 302 is pre-bakedon a hot plate for 2 minutes at 90° C.

[0228] Next, as shown in FIG. 18B, the resist layer 302 is light-exposedthrough a photo-mask 303. The essential part of the photo-mask 303 isshown in FIG. 19. As shown in the figure, the photo-mask 303 is composedof light shielding portions 311 each having an indefinite planar shapeand light transmitting portions 312 provided between the light shieldingportions 311. In addition, the photo-mask 303 has a light transmittingportion 313 used for forming a contact hole on the resist layer 302. Thelight shielding portions 311 are composed of Cr and disposed randomly.Moreover, the light shielding portions 311 are provided so that theapproximate ratio between the maximum length l₁ of a direction Y (alongitudinal direction of the display screen) and the maximum length w₁of a direction X (a lateral direction of the display screen) is 1:1. Thewidth of each of the light transmitting portions 312 is set to be about3-5 μm.

[0229] Subsequently, the light-exposed resist layer 302 is developed.Specifically, the substrate 301 having provided thereon the resist layer302 is immersed in a developer for a predetermined period. Then, thesubstrate 301 is taken out of the developer and cleaned in water. As aresult, as shown in FIG. 18c, a plurality of resist columns 304 areformed on the substrate 301. As a developer, for example, NMD-3 (brandname), available from Tokyo Ohka Kogyo Co., Ltd., may be used.

[0230] In the conventional fabricating method, water was removed byevaporation, and there was a step of heat treatment of the resistcolumns 304 at 150° C. Specifically, as shown in FIG. 18D, corners oftop of each of the resist columns 304 were heat-deformed to formprotrusions 305 each having a curved surface. Then, to cover theprotrusions 305, aluminum was deposited to cover the glass substrate 301to form a reflective film 306 (FIG. 18E). Al may be formed by asputtering method other than depositing. Other than Al, a reflectivematerial may be silver (Ag), nickel (Ni), or titanium (Ti), and also maybe an alloy of Al/tantalum (Ta) and the like.

[0231] Here, two adjacent resist columns 304 beside a narrow gap 308 ado not combine with each other by heat fusion. On the other hand, twoadjacent resist columns 304 beside a wide gap 308 b combine with eachother by heat fusion, resulting in a protrusion 310 having differenttilt angle distribution. Like the protrusion 310, if the reflectiveplate has a protrusion with tilt angle distribution different from thatof other protrusions 305, reflective properties become uneven within thesurface of the substrate. If a reflective plate in which reflectiveproperties are uneven within the surface of the substrate is applied toa display device, uneven brightness is recognized on the display screen.

[0232] In view of this, in the present embodiment, the developed resistcolumns 304 are subjected to UV hardening to prevent the combining ofthe adjacent resist columns 304. Specifically, the resist columns 304are irradiated by deep UV light (dominant wavelength: 254 nm).

[0233] Photo-resist that consists the resist columns 304 is highlyabsorptive to deep UV. Therefore, after the irradiation of deep UV, thesurface layer of each of the resist columns 304 are hardened. On theother hand, the internal of each of the resist columns 304 is nothardened, because deep UV has a short wavelength. That is to say, theinternal of each of the resist columns 304 keeps its initial heat fusionproperties, and there is a difference in fusion temperature between thesurface layer and internal of each of the resist columns 304. If theresist columns 304 having such conditions are subjected to heattreatment, the surface layer of each of the resist columns 304 becomessmoothly curved by heat fusion. However, since the surface layer ishardened, it does not flow as far as the adjacent resist columns 304.This enables to form protrusions 307 that are independent of one anotherand have uniform tilt angle distribution, and to fabricate a reflectiveplate without uneven reflective brightness, as shown in FIG. 18G.

[0234] As a light source for the irradiation of deep UV a low pressuremercury lamp is used. Irradiation period is 2 minutes, for example. Theheat fusion properties of the photo-resist in relation to irradiationperiod were studied. The result is that the longer the irradiationperiod was, the less the expansion amount of the resist columns 304 byheat fusion became. When irradiation period was more than 2 minutes, theexpansion amount of the resist columns 304 became constant. In addition,the thinner the resist layer 302 was (or the lower the resist columns304 were), the shorter the period of irradiation was before theexpansion amount of the resist columns 304 became constant. Therefore,when irradiation is more than a predetermined amount, similarly shapedprotrusions can be formed without depending on the amount ofirradiation, if heat fusion temperature is the same.

[0235] Thus, when the irradiation period of deep UV is controlled inaccordance with the thickness of the resist layer 302 (or the height ofeach of the resist columns 304), the formation of the protrusions havinguneven tilt angle distribution is prevented, and the reflective platehaving even reflective brightness is fabricated. In addition, theirradiation of deep UV with a low pressure mercury lamp also has afunction of discoloring. Therefore, even if a colored photo-resist isused, the photo-resist is discolored to form transparent protrusions.

[0236] In the conventional method of fabricating a reflective plate, theprotrusions were formed in the step of the first resist layer, and thesecond resist layer was further formed over the protrusions to have asmoothly curved surface for each of the protrusions. However, in themethod of fabricating the reflective plate of the present embodiment,the reflective plate is fabricated without forming the second resistlayer. As a result, the number of steps is reduced, realizing areduction in fabrication costs.

[0237] Moreover, in the conventional method of fabricating a reflectiveplate, a mask was required in the step of forming the second resistlayer in order to prevent the blockage of a contact hole which had beenformed in the step of the first resist layer. However, in the method offabricating the reflective plate of the present embodiment, since thecontact hole is formed simultaneously with the protrusions in the stepof the first resist layer, such a mask for the contact hole is notnecessary, realizing a reduction in the number of masks.

[0238] Embodiment 9

[0239] A method of fabricating a reflective plate of the presentembodiment will be described below.

[0240] The method of fabricating the reflective plate of the presentembodiment is different from the method of fabricating the reflectiveplate of Embodiment 8 in that an alkaline solution is used in hardeningthe surfaces of the resist columns in place of deep V. This is detailedas follows.

[0241] In the present embodiment, a 0.8% of alkaline solution, TMAH(trimethyl-ammonium-hydro-oxide, brand name: NMD-3, available from TokyoOhka Kogyo Co., Ltd.) is used. NMD-3 is usually used as a developer at aconcentration of 0.4 weight %.

[0242] The present inventors have found that by developing the resistlayer using a 0.8 weight % of NMD-3, the expansion amount of the resistcolumns in a lateral direction is reduced in the step of heat fusion.

[0243] Specifically, when using a p-type photo-resist, the resistcolumns obtained on the substrate after the steps of exposure anddevelopment are regions which are not light-exposed. It is presumed thatthese non-light-exposed photo-resists came into contact with and reactedto the alkaline solution, and thus the surface layer of each of theresist columns were hardened. As a result of this hardening, heatdeformation temperature at the surface layers of the resist columns wasmade high, and their flowability in readiness for heat deformation wasinhibited.

[0244] Therefore, in the method of fabricating the reflective plate ofthe present embodiment, since the melting properties of the photo-resistare controlled only by the usual step of development, an increase in thenumber of fabricating steps is inhibited in comparison to Embodiment 8,realizing a reduction in fabricating costs.

[0245] Usually, an alkaline solution used in development has a pH ofaround 12. If the resist layer is immersed in an alkaline solutionhaving a pH of 14, the expansion of the resist columns in a lateraldirection is inhibited in following heat treatment. For example, when agap between the resist columns was 5 μm, the gap was not filled.

[0246] In the present embodiment, although the increase of pH of thealkaline developer at the time of development was described as anexample, such a method may be also employed that the alkaline solutionis transformed into a vapor phase and the resist columns react to thevapor.

[0247] Embodiment 10

[0248] A reflective plate of the present embodiment is different fromthe reflective plate of Embodiment 1 in the planar shape of each of theprotrusions. Specifically, in Embodiment 1, each of the protrusions wasdescribed such that the approximate ratio between the maximum length L₁of a longitudinal direction of the display screen and the maximum lengthW₁ of a lateral direction of the display screen was 1:1. On the otherhand, in the present embodiment, the planar shape of a protrusion 321 isdesigned such that the ratio between the maximum length L₂ of alongitudinal direction (Y direction) of the display screen and themaximum length W₂ of a lateral direction (X direction) of the displayscreen is 1:2 as shown in FIG. 20.

[0249] When the maximum length of a longitudinal direction of thedisplay screen and the maximum length of a lateral direction of thedisplay screen are varied as mentioned above, the protrusion has suchtilt angle distribution as shown in FIG. 21. FIG. 21 is a graph showingthe relationship between the tilt angle (degree) of the protrusion andthe existence probability (%) of the tilt angle. A solid line (a) in thefigure denotes the tilt angle distribution of the protrusion in alateral direction. A solid line (b) denotes the tilt angle distributionof the protrusion in a longitudinal direction. As clearly shown in thefigure, the existence probability in a lateral direction has its peak ata lower tilt angle than the peak of the existence probability in alongitudinal direction. That is to say, it is recognized that, at a tiltangle in a lateral direction, light is reflected and dispersed in thenormal direction of the panel.

[0250] Therefore, the reflective plate of the present embodimentincreases the brightness of the display screen in a lateral direction,while decreases the brightness of the display screen in a longitudinaldirection. This enables it to provide directivity to reflectiveproperties.

[0251] Reflective type liquid crystal display devices having thereflective plate of the present embodiment is useful to mobile phones,for example. To mobile phones in which the viewing angle is wide in alongitudinal direction but narrow in a lateral direction, such areflective plate is useful that is capable of collecting light byreflecting and dispersing ambient light. This is because the reflectiveplate of the present embodiment is capable of providing directivity toreflected and dispersed light. Specifically, the shape of each of theprotrusions of the reflective plate is controlled such that the ratio ofthe maximum length of a longitudinal direction to the maximum length ofa lateral direction is 1.5 or more to 1.

[0252] In the fabrication of the reflective plate of the presentembodiment, a photo-mask shown in FIG. 22 is used in the step ofexposure. As shown in the figure, a light shielding portion 325 isprovided such that the approximate ratio between the maximum length l₂of Y direction (a longitudinal direction of the display screen) and themaximum length w₂ of X direction (a lateral direction of the displayscreen) is 1:2. In addition, the width of a light transmitting portion326 is 2-5 μm.

[0253] Embodiment 11

[0254] A reflective plate of the present embodiment is different fromthe reflective plate of Embodiment 1 in that the reflective plate of thepresent embodiment is a transflective reflective plate having lighttransmitting portions. FIG. 23 is a schematic cross sectional view ofthe transflective reflective plate of the present embodiment.

[0255] As shown in FIG. 23, a plurality of protrusions 331 made of alight-transmissive resist material are provided on a substrate 211. Agap portion 203 formed between the protrusions 331 has a function as alight transmitting portion to transmit light. In addition, a reflectivefilm 332 is provided on the protrusions 331. The reflective film 332 isnot provided on a low position 333 of each of the protrusions 331.

[0256] The low position 333 is a region at the foot of each of theprotrusions 331 having a tilt angle of from 15 to 90 degrees. When lightwith an incident angle of 50 degrees or more reaches the curved surfaceof a protrusion among the protrusions having a tilt angle of 15 degreesor more, the light is reflected in a direction perpendicular to thesubstrate. Although this enables to reflect light having a wide incidentangle in the normal direction, an optimum tilt angle of around 8 degrees(in this case, an incident angle of 25 degrees is reflected in aperpendicular direction) relatively reduces its existence probability.This reduces reflective properties throughout the surface of thesubstrate. That is to say, even if the reflective film is formed on thelow position 333 having a tilt angle of 15 degrees or more, reflectiveproperties are not improved. It is more likely that the low position 333is used as a part of the light transmitting portion in order to haveconstant reflective brightness, irrespective of viewing directions.

[0257] In addition, the protrusions 331 are preferably disposed 15 orless per area of 1×10⁴ μm². In a transflective type reflective plate,the gap portion 203 acting as the light transmitting portion constitutesmore than 50% of the pixel region. This is why the protrusions 331 arepreferably disposed 15 or less. When more than 15 of the protrusions 331are disposed, the protrusions 331 start to have regularity indisposition, ending up with a repeated pattern. This causes lightinterference, and the coloring of reflected light are recognized, whichis not preferable.

[0258] Embodiment 12

[0259] In the present embodiment, a study was conducted on how the shapeof the photo-mask and the thickness of the resist layer effect on theshape of each of the protrusions. It is to be noted that, although adiscussion is conducted using a protrusion whose planar shape iscircular for convenience in the present embodiment, the followingapplies to a protrusion whose planar shape is indefinite.

[0260] Using a photo-mask having circular light shielding portions,protrusions respectively having a diameter of 10, 20, 30, 40, 50, and 60μm were formed. The thickness of the resist layer was set to be 2 μm. Aresist material that was used was the same as in Embodiment 1.Irradiation period of deep UV using a low pressure mercury lamp was 2minutes in all the cases. The results are shown in FIG. 22.

[0261]FIG. 24 is a graph showing the relationship between the tilt angleof the protrusion and the existence probability of the tilt angle. Inthe graph, curved lines (a), (b), (c), and (d) are the existenceprobability of the tilt angle when the diameter of the protrusion is 5,10, 30, and 60 μm, respectively. The graph clearly shows that as thediameter of the protrusion became larger, the peak of the tilt angledistribution of the protrusion shifted to lower tilt angles. Reflectiveproperties increase in the range of ±25 degrees from the normaldirection as the existence probability of the tilt angle in the range of5 to 10 degrees becomes higher, in other words, as an area A (integralvalues when the tilt angle is in the range of 5 to 10 degrees) of anobliquely lined region (e) of the curved line (a) becomes larger.

[0262] Next, the contact angle of the protrusion was measured. Theresult is that the contact angle became smaller as the diameter of theprotrusion became larger. In addition, the relationship between thecontact angle and the area A was plotted to have a graph shown in FIG.25. As clearly shown in the graph, it was found out that, when thecontact angle of the protrusion was from 10 to 20 degrees, the area Abecame large, and reflective properties in the range of ±25 degrees fromthe normal direction became high. When the contact angle exceeded 20degrees, the existence probability of the tilt angle at from 5 to 10degrees, which are effective tilt angles, became low. These results showthat the contact angle is an important determinant for the tilt angledistribution of the protrusion.

[0263] In the case of a transflective reflective plate, when an anglebetween the substrate and each of the protrusions was from 10 to 40degrees, a reflective area was sufficiently adjusted, and reflectivebrightness was improved.

[0264] The contact angle can be controlled by the thickness of theresist layer, the maximum diameter of each of the protrusions, and heatproperties of a resist material. FIG. 26 is a graph showing therelationship between the maximum diameter (μm) of each of theprotrusions and the existence probability (%) of a tilt angle of from 5to 10 degrees. As clearly shown in the figure, the existence probabilitybecame high when the maximum diameter of each of the protrusions wasfrom 5 to 20 times larger than the thickness (2 μm) of the resist layer.When the maximum diameter was less than 5 times larger than thethickness of the resist layer, the contact angle exceeded 20 degrees,resulting in high diffusion properties. On the other hand, when themaximum diameter was more than 20 times larger than the thickness of theresist layer, the contact angle became 5 degrees or less and theprotrusions became flat, resulting in high specularity.

[0265] Thus, it has been recognized that once the thickness of theresist layer is determined, it is only required to set the maximumdiameter of each of the protrusions to be from 5 to 20 times larger thanthe thickness of the resist layer. In addition, when diffusionproperties are emphasized, the magnification of the maximum diameter ofeach of the protrusions with respect to the thickness of the resistlayer is lowered to the range of 5 to 10 times. When reflectivebrightness is emphasized, the magnification of the maximum diameter ofeach of the protrusions with respect to the thickness of the resistlayer is made high within the range. Thus, any design is possibleaccording to various performance conditions.

[0266] Embodiment 13

[0267] In the following, the present embodiment will be described.

[0268]FIG. 27 is a plan view showing protrusions of a reflective typeliquid crystal display device of the present embodiment. Embodiment 13employs a reflective type color liquid crystal display device using asystem of single polarizing plate. FIG. 28 is a cross sectional view ofthe reflective type liquid crystal display device taken along the lineA-A shown in FIG. 27.

[0269] As shown in FIGS. 27 and 28, the reflective type liquid crystaldisplay device of the present embodiment is composed of a substrate 401made of an insulative glass substrate, a counter substrate 402 tocounter the substrate 401, and a liquid crystal layer 403 providedbetween the substrate 401 and the counter substrate 402. A cell gapbetween the substrate 401 and the counter substrate 402 has apredetermined spacing.

[0270] On the inside of the counter substrate 402, a color filter 404 isprovided so that R (red) G (green) B (blue) respectively correspond toeach pixel. On the inside of the color filter 404, a common electrode405 made of a transparent conductive film is provided. On the outside ofthe counter substrate 402, an optical retardation plate 406 and apolarizing plate 407 are provided in this order.

[0271] On the substrate 401, a driving element 412, a plurality ofsource signal lines 413, a plurality of gate signal lines 414, and aplurality of protrusions 408 are provided.

[0272] The driving element 412 is connected to a source signal line 413through a source terminal 412 a. Also, the driving element 412 isconnected to a gate signal line 414 through a gate terminal 412 c.

[0273] The protrusions 408 are independent of one another, and betweenthe protrusions 408, a part of the surface of the substrate 401 isexposed. Hereinafter, the exposed part of the surface of the substrate401 is called a gap portion (bottom portion) 409. In addition, theprotrusions 408 are made of a resin which is a photosensitive material.This resin has the property of melt flow. Melt flow is a property or aphenomenon in which a material is softened by heat, causing a change inshape such as a round surface of a film or the flow of the film on thesubstrate. This melt flow realizes the smooth curving of the surface ofeach of the protrusions 408 in a protrusion-depression manner. Thisenables it to reduce light that is reflected in the regularly reflecteddirection and inhibit the appearance of a light source on the displayscreen, realizing preferable reflective properties. It is to be notedthat the protrusion-depression curving includes such a case where thesurface of each of the protrusions 408 is only curved in aprotrusion-like manner or a depression-like manner.

[0274] Above the substrate 401, a reflective film 410 is provided tocover the protrusions 408 and gap portions 409. This reflective film 410is formed by depositing aluminum of 0.1 μm thick, which is a metalreflective film having high reflectivity. Other than Al, a reflectivematerial may be Ag, Ni, or Ti, and also may be an alloy of Al/Ta and thelike.

[0275] The reflective film 410 is independently provided for each pixel.In addition, the reflective film 410 is electrically connected to adrain terminal 412 b of the driving element 412 through a contact hole411, and acts as a pixel electrode. The contact hole 411 is provided ineach of the protrusions 408. This configuration enables the drivingelement 412 on the substrate 401 to change a voltage applied between thereflective film 410 acting as a pixel electrode and the common electrode405, and thus realizes display operation.

[0276] In FIG. 28, incident light from outside the polarizing plate 407passes through the polarizing plate 407, the optical retardation plate406, the counter substrate 402, the color filter 404, the commonelectrode 405, and the liquid crystal layer 403, and then is reflectedby the reflective film 410 to pass in inverse order of them, so that thelight finally reaches the viewer of the reflective type liquid crystaldisplay device. During this while, a voltage applied on the liquidcrystal layer 403 can be controlled by the driving element 412 tocontrol light absorption and reflection.

[0277] In FIG. 29, how light is dispersed when seen in cross sectionalview of the reflective type liquid crystal display device of the presentinvention is shown. FIG. 29 is a cross sectional view schematicallyshowing the way incident light comes into the reflective type liquidcrystal display device and then is reflected.

[0278] As shown in FIG. 29, when incident light a, b, and c come intothe reflective type liquid crystal display device, the incident light ais widely back-dispersed to be a reflected light a′. The incident lightb reaches the flat gap portion 409, and thus is regularly reflected tobe a reflected light b′. The incident light c is forward-dispersed to bea reflected light c′. The incident light b which comes to the gapportion 409 in which the reflective film 410 is formed on the substrate401 is regularly reflected at the surface of the substrate to be thereflected light b′. When the gap portion 409 is large in area, theproportion of regular reflection increases. Therefore, the area of thegap portion 409 preferably forms a small proportion of the substrate asa whole. The gap portion 409 is accordingly made small in area to securereflective properties.

[0279]FIG. 30 is a plan view showing the height of a protrusion 408 fromthe surface of the substrate 401 using contour lines 415 and 416. Thecontour line 416 is a higher position than the contour line 415. Asshown in the figure, the contour lines of the protrusion 408 are aboutidentical to the shape of a border line (frame line of the protrusion408) 417 between the protrusion 408 and the gap portion 409 in which theprotrusion 408 is not provided. The surface of the protrusion 408 thatis arbitrarily and finely curved in a protrusion-depression manner ispointed in a direction perpendicular to the border line 417, that is tosay, in a direction perpendicular to a tangent line of the border lines417. The protrusion 408 has its surface deformed by a method such asmelt flow. During this while, the surface is roundly deformed when seenin a cross sectional view along the border line 417 between theprotrusion 408 and the gap portion 409, and therefore, the direction ofthe protrusion-depression curved surface depends on the border line 417.

[0280]FIG. 31 is a plan view showing the progress directions ofreflected light when the incident light a, b, and c come from the leftas viewed in the figure along the line A-A. A dotted symbol at the footof each arrow stands for a position where each of the incident lightreaches. As shown, the incident light is not reflected along the lineA-A, but reflected and dispersed in directions a′, b′, and c′.

[0281] On the other hand, reflective properties in the case where thegap portion has a straight-lined shape with a predetermined width are asfollows. FIG. 32 is a schematic cross sectional view showing theprogress directions of reflected light when incident light d, e, and fcome in. FIG. 33 is a plan view showing the progress directions ofreflected light when incident light d, e, and f come from the left asviewed in the figure along the line B-B.

[0282] As shown in FIG. 32, protrusions 421 are provided in astraight-lined shape in Y direction, and the gap portion 422 formedbetween the protrusions 421 is also provided in a straight-lined shapewith a predetermined width. When the incident light d, e, and f reachthe surface of the reflective film 410, they are respectivelyback-dispersed, regularly reflected, and forward-dispersed to beincident light d′, e′, and f′, respectively. This makes it seem as ifdispersion properties are preferable even with a reflective plate whichhas a straight-lined gap portion with a predetermined width. However, asshown in FIG. 33, when the reflective film 410 is seen in a plan view,the incident light d′, e′, and f′ are reflected only in a directionparallel to the same plane. This is because the tilted surface of eachof the protrusions 421 is square to the progress directions of theincident light d, e, and f when seen in a plan view. Therefore, when theprotrusions 421 are provided in a straight-lined shape in Y direction,light diffusion properties are not sufficiently secured.

[0283] Thus, the direction at which the protrusion-depression curvedsurface of each of the protrusions is pointed with respect to theprogress direction of incident light is an important factor for securingpreferable reflective properties. The direction of theprotrusion-depression curved surface of each of the protrusions dependson the border line between each of the protrusions and the gap portion,that is to say, the frame line of each of the protrusions. Therefore,preventing each part of the frame line from pointing in a constantdirection to the best possible degree is conducive to an improvement indispersion properties. In view of this, in the present embodiment, theprotrusion 408 is formed such that the shape of the border line betweenthe protrusion 408 and the gap portion 409 comprises a bay-like shape ora peninsula-like shape in order to realize preferable reflectiveproperties.

[0284] A further description on the protrusion 408 and the gap portion409 is as follows. FIG. 34 is a plan view showing the protrusion 408 andthe gap portion 409.

[0285] A bay-like curved line stands for a depressed part of theprotrusion 408 on a plane. Specifically, as shown in FIG. 34, thebay-like curved line may be such that the protrusion is smoothlydepressed along an arc as shown as symbols C and C′, the gap portion iswidely depressed inward as shown as symbols D and D′, or the gap portionis sharply depressed inward as shown as symbols E and E′.

[0286] A peninsula-like curved line stands for a protruding part of theprotrusion on the surface of the substrate. Specifically, as shown inFIG. 34, the peninsula-like curved line may be such that the protrusionsmoothly protrudes along an arc as shown as symbols F and F′, theprotrusion widely protrudes as shown as symbols G and G′, or theprotrusion sharply protrudes as shown as symbols H and H′. Thus, whenthe shape of the frame line of the protrusion 408 comprises such abay-like curved surface or a peninsula-like curved surface, theprotrusion-depression curved surface of the protrusion 408 points invarious directions, enabling an improvement in dispersion properties. Inaddition, a combination of a bay-like shape and a peninsula-like shaperealizes a reflective type liquid crystal display device havingpreferable reflective properties.

[0287] The planar shape of the protrusion 408 also can be specified asfollows. As shown in FIG. 35, on the frame line 417 of the protrusion408, tangent lines l₁, l₂, l₃, and l₄ of respective arbitrary contactpoints P, Q, R, and S are provided. When each of these tangent linesl₁-l₄ is represented by an angle in which Y direction (a longitudinaldirection of the pixel) is taken to be 0 degrees, the angle changes fromincrease to decrease or from decrease to increase at least three timesor more when the frame line 417 is circled. When the protrusion 408 hassuch a planar shape, preferable reflective properties are secured.

[0288] In addition, the frame line has a bending point T in which theangle with respect to Y direction changes from a plus sign to a minussign, a bending point U in which the angle changes from a minus sign toa plus sign, and a bending point V in which the angle changes from aplus sign to a minus sign.

[0289] When the frame line 417 has three or more of such bending pointsin which the angle with respect to Y direction changes from increase todecrease or from decrease to increase, the protrusion 408 that has aplanar shape in which a bay-like shape and a peninsula-like shape arecombined is formed.

[0290] The bay-like shape or the peninsula-like shape comprises a curvedline or a straight line that is angled with respect to a directionparallel or perpendicular to a longitudinal side of the pixel. Thisenables it to diffuse reflected light in various directions instead ofconstant directions, and to secure preferable reflective properties.

[0291] At least one of frame lines between the protrusion and a part ofthe surface of the substrate on which the protrusion is not provided mayform an indefinite two-dimensional closed region having a curved line ora straight line. In FIG. 35, three curved frame lines 417 a, 417 b, and417 c form indefinite two-dimensional closed regions. This configurationenables it to diffuse reflected light in various directions instead ofconstant directions and to secure preferable reflective properties.

[0292] As shown in FIG. 35, a driving element 412 provided in eachpixel, and a source signal line 413 and a gate signal line 414 bothelectrically connected to the driving element 412 are provided. In aconfiguration having the protrusion 408, the protrusion 408 ispreferably provided continuously on each of the signal lines in order toenhance insulation properties between a reflective film 418 on theprotrusion 408 and the source signal line 413 and the gate signal line414. In this case, if the frame line 417 c which is a border between theprotrusion 408 and the gap portion 409 is pointed in a directionparallel or perpendicular to the source signal line 413 and the gatesignal line 414, the surface of the protrusion 408 is pointed inconstant directions. This makes it impossible to secure preferablereflective properties. In view of this, the shape of the frame line 417c comprises a curved line or a straight line that is angled with respectto the source signal line 413 and the gate signal line 414. This enablesit to secure preferable reflective properties.

[0293] In addition, at least a part of the gap portion 409 formedbetween the protrusion 408 and the protrusion 408 may have a mesh-likeshape or an indefinite shape (an amebic shape). As shown in FIG. 36, amesh-like shape is such that a plurality of indefinitely shapedprotrusions 421 are provided on a substrate, and gap portions 422 formedbetween the protrusions 421 are provided in a mesh-like pattern with apredetermined width. With such protrusions 421, border lines between theprotrusions 421 and the gap portions 422 are pointed in variousdirections, making it possible to realize preferable reflectiveproperties.

[0294] As shown in FIG. 37, being an amebic shaped is a state in which acertain parts of each of gap portions 423 extend like the movements ofan ameba. Even when the gap portions 423 are amebic shaped, the samereflective properties are obtained.

[0295] A method of fabricating a reflective type liquid crystal displaydevice of the present embodiment will be now described based on adrawing. FIGS. 38A-38F are cross sectional views taken along the lineA-A in FIG. 27 in order to illustrate the method of fabricating thereflective plate of the present embodiment.

[0296] As shown in FIG. 38A, an acrylic p-type photosensitive materialwas spin-coated on a substrate 401 and pre-baked to form a resist layer431. The thickness of the resist layer 431 was made 2 μm. Next, as shownin FIG. 38B, the resist layer 431 was light-exposed through a photo-mask432. The mask that was used as the photo-mask 432 had a predeterminedpattern such that only regions having the shapes of the gap portions 409and the contact hole 411 were light-exposed.

[0297] Subsequently, using a developer which is a photosensitivematerial, the light-exposed resist layer 431 was developed, andpatterning was conducted to remove portions of the resist layer 431corresponding to the gap portions 409 and the contact hole 411 as shownin FIG. 38C. By this patterning, regions of the resist layercorresponding to the gap portions 409 were removed according to thepatterned shape of the light transmitting portion on the photo-mask 432.As a result, resist columns 433 remained on portions on which theprotrusions 408 were provided.

[0298] Next, the substrate 401 was heated on a hot plate of 140° C. for5 minutes to heat-deform the resist columns 433. As a result, theprotrusions 408 each having a curved surface and the gap portions 409were formed as shown in FIG. 38D. To harden the protrusions 408, thesubstrate 401 was further heated for one hour in an oven of 200° C. atwhich photosensitive materials are hardened.

[0299] Subsequently, as shown in FIG. 38E, an aluminum film of 0.2 μmthick was deposited and formed on the protrusions 408, and thenpatterned to be the shape of the pixel to form a reflective film 410.The reflective film 410 was formed along the protrusion-depressioncurved surface of each of the protrusions 408. Thus, the reflectiveplate having dispersion properties was formed.

[0300] In the formation of the reflective film 410, a reflective film410 for each pixel and the drain terminal 412 b of a driving element 412were electrically interconnected at a contact hole 411 in each pixel. Inthe step of photolithography and etching, when the reflective film 410is patterned to be the shape of the pixel, the driving element 412 cancontrol the potential of the reflective film 410 above each pixel. As aresult, it was made possible for the reflective film 410 to also act asa pixel electrode. Further over the substrate having thereon thereflective film 410, an alignment film was formed.

[0301] On a counter substrate 402, a color filter 404 was provided sothat each color of red (R), green (G), and blue (B) correspond to eachpixel. On the color filter 404, a common electrode (transparentelectrode) 405 made of ITO (indium tin oxide) was formed. On the commonelectrode 405, an alignment film was formed.

[0302] Next, the substrate 401 and the counter substrate 402 wereadhered to each other with a predetermined gap (about 4 μm) so that eachof the alignment films faced each other. Between the gap, a liquidcrystal material was enclosed to form a liquid crystal layer 403.

[0303] Further, on the outside of the counter substrate 402, an opticalretardation plate 406 and a polarizing plate 407 were adhered in thisorder. Thus, the reflective type liquid crystal display device wascompleted.

[0304] As a display portion, this reflective type liquid crystal displaydevice can compose display devices for computers, mobile informationterminals, mobile phones, and the like.

[0305] In addition, in the present embodiment, although heating wasemployed to control the shape of a material that forms the protrusions,other methods may be employed to control the shape of theprotrusion-depression curved surface of each of the protrusions. Forexample, when such a resin is used that a crosslinking between moleculescan be severed by light exposure, a film is softened and flows on thesubstrate. This phenomenon similar to that obtained by melt flow canalso be obtained by light exposure, making it possible to control theshape of the protrusions.

[0306] Embodiment 14

[0307] The present embodiment will be described with reference todrawings. FIG. 39 is a plan view of a pixel region of a transflectivetype liquid crystal display device of the present embodiment. FIG. 40 isa cross sectional view of the transflective type liquid crystal displaydevice taken along the line J-J′ shown in FIG. 39.

[0308] The transflective type liquid crystal display device of thepresent embodiment is not a transflective type liquid crystal that usesa transflective film, but employs a system in which a part of the pixelregion has a reflective film for reflection display and the rest part ofthe pixel region performs light-transmission display. In the presentembodiment, the pixel region is a region that contributes to displayingas a pixel, and a region that does not contribute to display operationin a pixel pitch is not considered as the pixel region. Therefore, thepixel region is composed of a reflective region and a transmittingregion, both contributing to display operation.

[0309] The transflective type liquid crystal display device of thepresent embodiment and the reflective type liquid crystal display deviceof Embodiment 13 have a lot in common. Therefore, only their differencewill be described. In the transflective type liquid crystal displaydevice of the present embodiment, the substrate 401 and the protrusions408 are the same as in Embodiment 1. A reflective film 436 is differentfrom that in Embodiment 13 in that the reflective film 436 is notprovided on the gap portion 409 on which a protrusion 408 among theprotrusions 408 is not provided. On the gap portion 409, a transparentelectrode 432 made of ITO is formed. The transparent electrode 432 maybe made of a transparent conductive film other than ITO. The transparentelectrode 432 is also provided on the reflective film 436 so that thetransparent electrode 432 and the reflective film 436 have the samepotential. Thus, the reflective film 436 is provided only on theprotrusions 408 to make them reflective portions, and the gap portion409 on which the protrusion 408 is not provided acts as a lighttransmitting portion. This enables the effective use of the flat gapportion 409 which does not diffuse reflected light as a lighttransmitting portion. As a result, preferable reflective properties andlight-transmission properties are realized.

[0310] Display is operated by reflection in the same manner as thereflective type liquid crystal display device. As shown in FIG. 40, fordisplay operation at the light transmitting portion, an opticalretardation plate 406 and a polarizing plate 407 are provided on theoutside of the substrate 401. At the time of light-transmission display,incident light from outside a polarizing plate 437 passes through anoptical retardation plate 438, the substrate 401, the transparentelectrode 432, a liquid crystal layer 403, a common electrode 405, acolor filter 404, a counter substrate 402, the optical retardation plate406, and the polarizing plate 407, and finally reaches the viewer of thetransflective type liquid crystal display device. During this while, bycontrolling a voltage between the transparent electrode 435 and thecommon electrode 405, liquid crystal is controlled and thus display isoperated. Note that a back light is omitted in the transflective typeliquid crystal display device shown in FIG. 40.

[0311] In the transflective type liquid crystal display device of thepresent embodiment, the reflective film 436 is provided on theprotrusions 408. The protrusions 408 and those in Embodiment 13 have thesame features to obtain preferable reflective properties.

[0312] Specifically, to secure preferable reflective properties, the gapportion 409 or a border line (frame line 417) between one of theprotrusions 408 and the gap portion 409 on which the protrusion 408 isnot provided have the following configurations. 1) The shape of theborder line comprises a bay-like shape or a peninsula-like shape. 2) Theborder line forms at least one closed curved-line, and when a tangentline drawn along the curved line on the substrate is represented by anangle in which a longitudinal direction of the pixel is taken to be 0degrees, the angle changes from increase to decrease or from decrease toincrease at least three times when the curved line is circled. 3) Atleast one border line forms indefinite two-dimensional closed regionshaving a curved line or a straight line. 4) The shape of the border linecomprises a curved line or a straight line that is angled with respectto a direction parallel or perpendicular to a longitudinal side of apixel. 5) The shape of the border line comprises a curved line or astraight line, both angled with respect to the signal lines. Inaddition, a part of the pixel in which the protrusion is not providedmay be mesh-like shaped or indefinitely shaped (ameba-like shaped).

[0313] Embodiment 15

[0314] In a transflective type liquid crystal display device of thepresent embodiment, a reflective portion and a light transmittingportion have respective regions in a pixel. By adjusting the area of thereflective film, each area of the reflective portion and the lighttransmitting portion is changed. This enables a design in which eithertransmissivity or reflectivity is emphasized. In FIG. 41, thetransflective type liquid crystal display device of the presentembodiment is shown that has higher transmissivity than that inEmbodiment 14. FIG. 41 is a plan view of a pixel. FIG. 42 is a crosssectional view taken along the line K-K shown in FIG. 41.

[0315] As shown in FIG. 41, around the center of a pixel region, a lighttransmitting portion 442 to transmit light from a back light isprovided. This light transmitting portion 442 corresponds to a part ofthe pixel region in Embodiment 14 in which the protrusion around thecenter of the pixel region and the reflective film on the protrusion areremoved (see FIGS. 39 and 40). That is to say, the light transmittingportion 442 is a region formed such that the protrusion around thecenter of the pixel region is removed to have a large light transmissionregion.

[0316] In the periphery of the light transmitting portion 442, aprotrusion the surface of which has a reflective film is provided. Theregion in which the protrusion is provided acts as a reflective portion441.

[0317] It is to be noted that the present embodiment has the samefeatures as those of Embodiment 14 to have preferable reflectiveproperties. For example, a border between a reflective portion 441 and alight transmitting portion 442 is bay-like shaped or peninsula-likeshaped. Therefore, preferable reflective properties are obtained in thepresent embodiment.

[0318] Embodiment 16

[0319] When a transflective type liquid crystal display device comprisesan active matrix substrate in which a pixel has an auxiliary capacitorelectrode therein, a metal film is usually used as the auxiliarycapacitor electrode. Therefore, portions of the auxiliary capacitorelectrode can not be used as light transmitting portions. In view ofthis, to make the most of the regions of the auxiliary capacitorelectrode as reflective portions, it is preferable that at least a partof the planar shape of the auxiliary capacitor electrode is closelyanalogous to the planar shape of each of the protrusions. An example ofthe transflective type liquid crystal display device having such aconfiguration is shown in FIG. 43. FIG. 43 is a plan view of thetransflective type liquid crystal display device of the presentembodiment. FIG. 44 shows a pixel having a common quadrangle auxiliarycapacitor electrode.

[0320] As shown in FIG. 44, above an auxiliary capacitor electrode 451,there are many regions of a gap portion 409. Accordingly, incident lightis specular-reflected by the auxiliary capacitor electrode 451, creatinga tendency for display to be dark. On the other hand, as shown in FIG.43, when the planar shape of the auxiliary capacitor electrode 452 ischanged according to the shape of the protrusion 408, the auxiliarycapacitor electrode 452 is not exposed to the gap portion 409. Thisenables it to prevent the specular reflection of light and utilize theperiphery of the auxiliary capacitor electrode 452 for obtainingpreferable reflective properties. As a result, a transflective typeliquid crystal display device having further improved displayperformance is realized.

[0321] Embodiment 17

[0322] To appropriately control reflectivity and transmissivity in atransflective type liquid crystal display device, adjusting the area ofthe reflective film is effective. In Embodiment 13, the height of eachof the protrusions 408 was represented by contour lines 415 and 416. Asthus described, each of the contour lines of the protrusion is almostalong a border line (frame line of the protrusion) between theprotrusion and the gap portion. Therefore, when a part of a reflectivefilm adjacent to the gap portion are removed along the contour lines,such a state is secured that the protrusion-depression curved surface ofthe protrusion is pointed in various directions. This state is the sameas in Embodiments 13 and 14. This enables it to secure the samepreferable dispersion properties as those in Embodiment 13, even if thearea of the light transmitting portion is increased.

[0323] An example of a transflective type liquid crystal display devicehaving such a configuration is shown in FIG. 45. FIG. 45 is a plan viewof the transflective type liquid crystal display device. FIG. 46 is across sectional view taken along the line L-L shown in FIG. 45.

[0324] A border line 462 between the reflective film and a portion onwhich the reflective film is not provided is formed to be closelyanalogous to the shape of a border line 461 between the protrusion 408and the gap portion 409. In FIG. 45, regions with slanted lines are thegap portion 409 on which the protrusion 408 is not provided, dottedregions are portions on which the reflective film is provided, and whiteregions between the two regions are portions of the protrusion 408 onwhich the reflective film is not provided.

[0325] The border line 462 between the reflective film and the portionon which the reflective film is not provided may be bay-like shapedand/or peninsula-like shaped, both closely analogous to the border linebetween the protrusion 408 and the gap portion 409. Or else, 1) Theborder line forms at least one closed curved-line, and when a tangentline drawn along the curved line on the substrate is represented by anangle in which a longitudinal direction of a pixel is taken to be 0degrees, the angle changes from increase to decrease or from decrease toincrease at least three times when the curved line is circled. 2) Atleast one border line forms indefinite two-dimensional closed regionshaving a curved line or a straight line. 3) The shape of the border linecomprises a curved line or a straight line that is angled with respectto a direction parallel or perpendicular to a longitudinal side of apixel. 4) The shape of the border line comprises a curved line or astraight line, both angled with respect to the signal lines. As aresult, preferable reflective properties are realized.

[0326] Embodiment 18

[0327] In the above-described embodiments, although the protrusions wererandomly disposed in a reflective plate, the present invention is notlimited to this. FIG. 47 is a plan view schematically showing theprotrusions aligned in a regular spiral pattern. As shown in the figure,the protrusions 408 are provided in positions of meeting the relation ofFibonacci series. Even when the protrusions 408 are aligned in such amanner, the shape of the gap portion between the protrusions 408comprises a curved line with a predetermined width and/or a broken linewith a predetermined width. When the reflective plate of the presentembodiment is applied to a liquid crystal display device, theabove-described alignment may be formed pixel by pixel or in each R-G-Bunit.

[0328] Other items

[0329] In the above-described embodiments, although a p-typephoto-resist was used as a resist material, an n-type photo-resist maybe used in the present invention.

[0330] In addition, in the above-described embodiments, although aphotosensitive resin was used as a material to be formed into theprotrusions, the present invention is not limited to this. For example,the protrusions can be formed as follows. A non-photosensitive resinlayer is formed on a substrate, and a resist is formed over thesubstrate. Thereafter, photolithography is conducted and the resin isetched. Even with this method, the same advantageous effects as theabove-described embodiments are obtained.

[0331] In addition, in the above-described embodiments, although atransparent glass was used as the substrate, the substrate may be madeof a resin such as plastic. In addition, the substrate on the side ofwhich a reflective plate of a reflective type liquid crystal displaydevice is provided may be made of an opaque silicon.

[0332] In addition to reflective type color liquid crystal devices usinga single polarizing plate, the above-described embodiments can beapplied to other liquid crystal display devices such as guest-host typeliquid crystal devices in which liquid crystal contains a dichroic dye.Similarly, the above-described embodiments can be applied to one-coloredliquid crystal display devices that do not display images in color.

[0333] In addition to what is called an active matrix system in which adriving element on a substrate corresponding to each pixel controls avoltage applied on each pixel, the liquid crystal display device of thepresent invention may employ a passive system such as a super twistednematic (STN) system, in which each pixel does not have a drivingelement.

[0334] In addition, in the above-described embodiments, a reflectivetype liquid crystal display device and a transflective type liquidcrystal display device both using liquid crystal were used to describehow to control the transmission and absorption of light. However, thepresent invention is not limited to this. For example, electrophoresisdisplays may be employed in which the transmission and absorption oflight is controlled such that fine particles dispersed in a solution aremoved by a potential. The reflective plate of the present invention canbe applied to other display devices than liquid crystal display devices.

[0335] In addition, the reflective film of the present invention can bemade half mirrored if the film is appropriately thick. This makes itpossible for the reflective film to be a transflective film capable ofhaving both light reflectivity and light transmissivity. As a result, atransflective type display device is realized only by replacing a commonreflective film with the transflective film.

[0336] Industrial Applicability

[0337] The objects of the present invention are fully accomplished bythe configurations of the invention described above.

[0338] Specifically, according to the reflective plate of the presentinvention, the shape of the gap portion comprises a curved line having apredetermined width and/or a broken line having a predetermined width,and therefore, the flat gap portion is made small in area by forming asingle resist layer. As a result, reflective brightness is made constantirrespective of viewing directions, and dispersion properties areimproved.

[0339] In addition, the display device having the reflective plate makesit possible to adjust viewing angles and reflective brightness accordingto application. This is realized by changing the tilt angle distributionof each of the protrusions of the reflective plate. As a result, displayperformance is improved.

[0340] In addition, the fabricating method of the present invention hassmaller number of steps than conventional fabricating methods. Thismakes it possible to reduce fabrication costs and fabricate a reflectiveplate excellent in dispersion properties with improved yields.

What is claimed is:
 1. A reflective plate comprising a substrate, aplurality of protrusions each formed on the substrate and having acurved surface, and a reflective film formed on the substrate having theprotrusions, wherein a planar shape of each of the protrusions isnon-circular, and when a frame line of the planar shape of each of theprotrusions is divided into fine line segments, the line segments arepointed in all directions or in predetermined directions.
 2. Areflective plate comprising a substrate, a plurality of protrusions eachformed on the substrate and having a curved surface, and a reflectivefilm formed on the substrate having the protrusions, wherein a planarshape of each of the protrusions is indefinite, and a shape of a gapportion between the protrusions comprises a curved line having apredetermined width and/or a broken line having a predetermined width.3. The reflective plate according to claim 2, wherein a width of the gapportion is uniform.
 4. The reflective plate according to claim 2,wherein the width of the gap portion is in a range of 1 to 10 μm.
 5. Thereflective plate according to claim 2, wherein a maximum diameter ofeach of the protrusions is in a range of 15 to 40 μm.
 6. The reflectiveplate according to claim 2, wherein a height of each of the protrusionsis in a range of 1.2 to 4 μm.
 7. The reflective plate according to claim2, wherein a maximum diameter of each of the protrusions is from 5 to 20times larger than the height of each of the protrusions.
 8. Thereflective plate according to claim 2, wherein a contact angle formed bya surface of each of the protrusions and a surface of the substrate at acontact line is in a range of 10 to 25 degrees.
 9. The reflective plateaccording to claim 2, wherein the protrusions are provided 30 or lessper area of 1×10⁴ μm².
 10. The reflective plate according to claim 2,wherein the protrusions are provided in positions of meeting a relationof Fibonacci series.
 11. The reflective plate according to claim 2,wherein the substrate is light-transmissive, and the gap portion is notcoated with the reflective film and is a light transmission region. 12.The reflective plate according to claim 11, wherein the protrusions aretransmissive, and a low position portion of each of the protrusions isnot coated with the reflective film.
 13. The reflective plate accordingto claim 11, wherein, when an angle formed by the substrate and atangent line in contact with a surface of each of the protrusions istaken to be a tilt angle, the low position portion has a tilt angle of15 degrees or more.
 14. The reflective plate according to claim 11,wherein a width of the gap portion is in a range of 1 to 20 μm.
 15. Thereflective plate according to claim 11, wherein a contact angle formedby a surface of each of the protrusions and a surface of the substrateat a contact line is in a range of 10 to 40 degrees.
 16. The reflectiveplate according to claim 11, wherein the protrusions are provided 15 orless per area of 1×10⁴ μm².
 17. A reflective plate comprising asubstrate, a plurality of protrusions each formed on the substrate andhaving a curved surface, and a reflective film formed on the substratehaving the protrusions, wherein a shape of a frame line of each of theprotrusions comprises a bay-like curved line or a peninsula-like curvedline.
 18. A reflective plate comprising a substrate, a plurality ofprotrusions each formed on the substrate and having a curved surface,and a reflective film formed on the substrate having the protrusions,wherein a planar shape of each of the protrusions is indefinite, and atleast a part of the gap portion between the protrusions is provided in amesh-like pattern or indefinite pattern.
 19. A reflective platecomprising a substrate, a plurality of protrusions each formed on thesubstrate and having a curved surface, and a reflective film formed onthe substrate having the protrusions, wherein a frame line of each ofthe protrusions forms at least one closed curved-line; and wherein, whena tangent line drawn along the closed curved-line on the substrate isrepresented by an angle in which a predetermined direction is taken tobe 0 degrees, the angle changes from increase to decrease or fromdecrease to increase at least three times when the closed curved-line iscircled.
 20. A reflective plate comprising a substrate, a plurality ofprotrusions each formed on the substrate and having a curved surface,and a reflective film formed on the substrate having the protrusions,wherein at least one of frame lines of the protrusions forms anindefinite two-dimensional closed region having a curved line or astraight line.
 21. A method of fabricating a reflective plate,comprising: forming a layer of a resin on a substrate; forming aplurality of column-shaped portions each having a rectangle crosssectional shape by patterning the layer of the resin to be apredetermined shape so that a part of a surface of the substrate isexposed; imparting an affinity for the resin to the exposed part of thesurface of the substrate by surface treatment, the exposed part beingbetween the column-shaped portions; forming a plurality of protrusionseach having a curved surface by heat treatment to the plurality ofcolumn-shaped portions so that the resin flows on the exposed part ofthe surface of the substrate; and forming a reflective film at least onthe protrusions.
 22. The method according to claim 21, wherein the stepof imparting an affinity for the resin to the exposed part of thesurface of the substrate is such that the exposed part of the surface ofthe substrate comes into contact with one functional group selected fromfunctional groups shown in a general formula (1) below and a compoundhaving a functional group that shows an affinity for the resin, so thata functional group having active hydrogen that exists on the exposedpart reacts to the functional group selected from the functional groupsshown in the general formula (1) below in order to form a film made ofthe compound.

(In this formula, a symbol A denotes one atom selected from a groupconsisting of silicon, germanium, tin, titanium, and zirconium. A symbolX denotes one functional group selected from a group consisting ofhalogen, an alkoxy group, and an isocyanate group.)
 23. The methodaccording to claim 21, wherein the step of imparting an affinity is suchthat the exposed part of the surface of the substrate is irradiated byan ultraviolet ray.
 24. A method of fabricating a reflective plate,comprising: forming a layer of a resin on a substrate; forming aplurality of column-shaped portions each having a rectangle crosssectional shape by patterning the layer of the resin to be apredetermined shape so that a part of a surface of the substrate isexposed; plasticizing the column-shaped portions by applying aplasticizer on the column-shaped portions; forming a plurality ofprotrusions each having a curved surface by heat treatment to theplurality of column-shaped portions so that the resin flows on theexposed part of the surface of the substrate; and forming a reflectivefilm at least on the protrusions.
 25. A method of fabricating areflective plate, comprising: forming a layer of a resin on a substrate;forming a plurality of column-shaped portions each having a rectanglecross sectional shape by patterning the layer of the resin to be apredetermined shape so that a part of a surface of the substrate isexposed; hardening surface layers of the column-shaped portions; forminga plurality of protrusions each having a curved surface by heattreatment to the plurality of column-shaped portions so that the resinflows on the exposed part of the surface of the substrate; and forming areflective film at least on the protrusions.
 26. The method according toclaim 25, wherein the step of hardening the surface layers of thecolumn-shaped portions is such that the column-shaped portions areirradiated by an ultraviolet ray having a dominant wavelength of 300 nmor less.
 27. The method according to claim 25, wherein the step ofhardening the surface layers of the column-shaped portions is such thatan alkaline solution is applied on the column-shaped portions.
 28. Amethod of fabricating a reflective plate having a gap portion comprisinga curved line and/or a broken line between a plurality of protrusions,the curved line and the broken line having a predetermined width,comprising: forming a photosensitive resin layer on a substrate;light-exposing the photosensitive resin layer through a mask having apattern wherein a shape of a light shielding portion or a lighttransmitting portion comprises a curved line having a predeterminedwidth and/or a broken line having a predetermined width; forming aplurality of column-shaped portions by developing the light-exposedphotosensitive resin layer so that a part of a surface of the substrateis exposed; forming the plurality of protrusions each having a curvedsurface by heat treatment to the plurality of column-shaped portions;and forming a reflective film at least on the protrusions.
 29. Themethod according to claim 28, wherein the mask has a pattern such that awidth of the light shielding portion or the light transmitting portionis 3 μm or less.
 30. A method of fabricating a reflective plate,comprising: forming a layer of a photosensitive resin on a substrate;light-exposing the layer of the photosensitive resin through a maskhaving a light shielding portion having a predetermined pattern or alight transmitting portion having a predetermined pattern; forming aplurality of column-shaped portions by developing the light-exposedphotosensitive resin layer so that a part of a surface of the substrateis exposed; imparting an affinity for the photosensitive resin to theexposed part of the surface of the substrate by heat treatment, theexposed part being between the column-shaped portions; forming aplurality of protrusions each having a curved surface by heat treatmentto the plurality of column-shaped portions so that the photosensitiveresin flows on the exposed part of the surface of the substrate; andforming a reflective film at least on the protrusions, wherein, as themask, such a mask is used that a planar shape of the light shieldingportion or the light transmitting portion is non-circular, and when aframe line of the planar shape of the light shielding portion or thelight transmitting portion is divided into fine line segments, the linesegments are pointed in all directions or in predetermined directions.31. A display device comprising a substrate having a plurality ofnonlinear elements and wirings formed on the substrate, a plurality ofprotrusions each formed on the substrate and having a curved surface,and a reflective film formed on the substrate having the protrusions,wherein a planar shape of each of the protrusions is non-circular, andwhen a frame line of the planar shape of each of the protrusions isdivided into fine line segments, the line segments are pointed in alldirections or in predetermined directions.
 32. A display devicecomprising a substrate having a plurality of nonlinear elements andwirings formed on the substrate, a plurality of protrusions each formedon the substrate and having a curved surface, and a reflective filmformed on the substrate having the protrusions, wherein a gap portion isprovided between the protrusions, and a shape of the gap portioncomprises a curved line having a predetermined width and/or a brokenline having a predetermined width.
 33. The display device according toclaim 32, wherein a width of the gap portion is uniform.
 34. The displaydevice according to claim 32, wherein the width of the gap portion is ina range of 1 to 10 μm.
 35. The display device according to claim 32,wherein a maximum diameter of each of the protrusions is in a range of15 to 40 μm.
 36. The display device according to claim 32, wherein aheight of each of the protrusions is in a range of 1.2 to 4 μm.
 37. Thedisplay device according to claim 32, wherein a maximum diameter of eachof the protrusions is from 5 to 20 times larger than the height of eachof the protrusions.
 38. The display device according to claim 32,wherein a contact angle formed by a surface of the protrusion and asurface of the substrate at a contact line is in a range of 10 to 25degrees.
 39. The display device according to claim 32, wherein theprotrusions are provided 30 or less per area of 1×10⁴ μm².
 40. Thedisplay device according to claim 32, wherein the protrusions areprovided in positions of meeting a relation of Fibonacci series.
 41. Thedisplay device according to claim 32, wherein, on the substrate, anauxiliary capacitor electrode electrically connected to the nonlinearelements is provided; and wherein, above the auxiliary capacitorelectrode, at least one of the protrusions is provided so that at leasta part of the gap portion overlaps with a periphery of the auxiliarycapacitor electrode.
 42. The display device according to claim 32,wherein a planar shape of the auxiliary capacitor electrode is polygonalhaving at least one reentrant angle.
 43. The display device according toclaim 32, wherein, on the substrate, an auxiliary capacitor electrodeelectrically connected to the nonlinear elements is provided; andwherein a width of a part of a gap portion above the auxiliary capacitorelectrode is narrower than a width of a rest part of the gap portion.44. The display device according to claim 32, wherein, on the substrate,an auxiliary capacitor electrode electrically connected to the nonlinearelements is provided; and wherein a maximum diameter of each ofprotrusions among the protrusions above the auxiliary capacitorelectrode is smaller than a maximum diameter of each of a rest of theprotrusions.
 45. The display device according to claim 32, wherein thesubstrate is light-transmissive; and wherein the gap portion is notcoated with the reflective film and is a light transmission region. 46.The display device according to claim 45, wherein the protrusions arelight-transmissive, and a low position portion of each of theprotrusions is not coated with the reflective film.
 47. The displaydevice according to claim 45, wherein, when an angle formed by thesubstrate and a tangent line in contact with a surface of each of theprotrusions is taken to be a tilt angle, a low position portion has atilt angle of 15 degrees or more.
 48. The display device according toclaim 45, wherein a width of the gap portion is in a range of 1 to 20μm.
 49. The display device according to claim 45, wherein a height ofeach of the protrusions is in a range of 1.2 to 4 μm.
 50. The displaydevice according to claim 45, wherein a contact angle formed by asurface of each of the protrusions and a surface of the substrate at acontact line is in a range of 10 to 40 degrees.
 51. The display deviceaccording to claim 45, wherein the protrusions are provided 15 or lessper area of 1×10⁴ μm².
 52. A display device comprising a substratehaving a plurality of nonlinear elements and wirings formed on thesubstrate, a plurality of protrusions each formed on the substrate andhaving a curved surface, and a reflective film formed on the substratehaving the protrusions, wherein a shape of a frame line of each of theprotrusions comprises a bay-like curved line or a peninsula-like curvedline.
 53. A display device comprising a substrate having a plurality ofnonlinear elements and wirings formed on the substrate, a plurality ofprotrusions each formed on the substrate and having a curved surface,and a reflective film formed on the substrate having the protrusions,wherein a planar shape of each of the protrusions is indefinite, and atleast a part of the gap portion between the protrusions is provided in amesh-like pattern or indefinite pattern.
 54. A display device comprisinga substrate having a plurality of nonlinear elements and wirings formedon the substrate, a plurality of protrusions each formed on thesubstrate and having a curved surface, and a reflective film formed onthe substrate having the protrusions, wherein a frame line of each ofthe protrusions forms at least one closed curved-line; and wherein, whena tangent line drawn along the closed curved-line on the substrate isrepresented by an angle in which a predetermined direction is taken tobe 0 degrees, the angle changes from increase to decrease or fromdecrease to increase at least three times when the closed curved-line iscircled.
 55. A display device comprising a substrate having a pluralityof nonlinear elements and wirings formed on the substrate, a pluralityof protrusions each formed on the substrate and having a curved surface,and a reflective film formed on the substrate having the protrusions,wherein at least one of frame lines of each of the protrusions forms anindefinite two-dimensional closed region having a curved line or astraight line.
 56. The display device according to claim 55, wherein oneof the frame lines of each of the protrusions comprises a curved line ora straight line that is angled with respect to a direction parallel orperpendicular to a longitudinal side of a pixel.
 57. A display devicecomprising a substrate having a plurality of nonlinear elements andwirings formed on the substrate, a plurality of protrusions each formedon the substrate and having a curved surface, and a reflective filmformed on the substrate having the protrusions, wherein a frame line ofeach of the protrusions comprises a curved line or a straight line thatis angled with respect to the wirings.
 58. A protrusion-depressionstructure comprising a substrate, a plurality of protrusions each formedon the substrate and having a curved surface, wherein a planar shape ofeach of the protrusions is non-circular, and when a frame line of theplanar shape of each of the protrusions is divided into fine linesegments, the line segments are pointed in all directions or inpredetermined directions.
 59. A protrusion-depression structurecomprising a substrate, a plurality of protrusions each formed on thesubstrate and having a curved surface, wherein a gap portion is providedbetween the protrusions, and a shape of the gap portion comprises acurved line having a predetermined width and/or a broken line having apredetermined width.
 60. A protrusion-depression structure comprising asubstrate, a plurality of protrusions each formed on the substrate andhaving a curved surface, wherein a shape of a frame line of each of theprotrusions comprises a bay-like curved line or a peninsula-like curvedline.
 61. A protrusion-depression structure comprising a substrate, aplurality of protrusions each formed on the substrate and having acurved surface, wherein a planar shape of each of the protrusions isindefinite, and at least a part of the gap portion between theprotrusions is provided in a mesh-like pattern or indefinite pattern.62. A protrusion-depression structure comprising a substrate, aplurality of protrusions each formed on the substrate and having acurved surface, wherein a frame line of each of the protrusions forms atleast one closed curved-line; and wherein, when a tangent line drawnalong the closed curved-line on the substrate is represented by an anglein which a predetermined direction is taken to be 0 degrees, the anglechanges from increase to decrease or from decrease to increase at leastthree times when the closed curved-line is circled.
 63. Aprotrusion-depression structure comprising a substrate, a plurality ofprotrusions each formed on the substrate and having a curved surface,wherein at least one of frame lines of the protrusions forms anindefinite two-dimensional closed region having a curved line or astraight line.